Apparatus and methods for communicatively coupling field devices to controllers in a process control system using a distributed marshaling architecture

ABSTRACT

Apparatus, systems, and methods for communicating data between a controller and a multiplicity of field devices operating in a process plant are provided. The system includes distributed marshaling modules coupled by a head-end unit to I/O cards in communication with the controller. The distributed marshaling modules communicate with the field devices via respective electronic marshaling components converting signals between the field devices and the I/O cards. The distributed marshaling modules are coupled to the head-end unit by a ring communication architecture, such that the distributed marshaling modules may each be located relatively proximate to the field devices to which they are coupled.

RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 15/332,355, entitled “Apparatus and Methods for CommunicativelyCoupling Field Devices to Controllers in a Process Control System Usinga Distributed Marshaling Architecture,” filed on Oct. 24, 2016, theentire disclosure of which is hereby incorporated by reference herein.

TECHNICAL FIELD

The present disclosure relates generally to process plants and processcontrol systems, and more particularly, to commissioning of fielddevices and loops of process plants and process control systems.

BACKGROUND

Distributed process control systems, like those used in chemical,petroleum, industrial or other process plants to manufacture, refine,transform, generate, or produce physical materials or products typicallyinclude one or more process controllers communicatively coupled to oneor more field devices via analog, digital or combined analog/digitalbuses, or via a wireless communication link or network. The fielddevices, which may be, for example, valves, valve positioners, switchesand transmitters (e.g., temperature, pressure, level and flow ratesensors), are located within the process environment and generallyperform physical or process control functions such as opening or closingvalves, measuring process and/or environmental parameters such astemperature or pressure, etc. to control one or more processes executingwithin the process plant or system. Smart field devices, such as thefield devices conforming to the well-known Fieldbus protocol may alsoperform control calculations, alarming functions, and other controlfunctions commonly implemented within the controller. The processcontrollers, which are also typically located within the plantenvironment, receive signals indicative of process measurements made bythe field devices and/or other information pertaining to the fielddevices and execute a controller application that runs, for example,different control modules which make process control decisions, generatecontrol signals based on the received information and coordinate withthe control modules or blocks being performed in the field devices, suchas HART®, WirelessHART®, and FOUNDATION® Fieldbus field devices. Thecontrol modules in the controller send the control signals over thecommunication lines or links to the field devices to thereby control theoperation of at least a portion of the process plant or system, e.g., tocontrol at least a portion of one or more industrial processes runningor executing within the plant or system. For example, the controllersand the field devices control at least a portion of a process beingcontrolled by the process plant or system. I/O devices, which are alsotypically located within the plant environment, typically are disposedbetween a controller and one or more field devices, and enablecommunications there between, e.g. by converting electrical signals intodigital values and vice versa. As utilized herein, field devices,controllers, and I/O devices are generally referred to as “processcontrol devices,” and are generally located, disposed, or installed in afield environment of a process control system or plant.

Information from the field devices and the controller is usually madeavailable over a data highway or communication network to one or moreother hardware devices, such as operator workstations, personalcomputers or computing devices, data historians, report generators,centralized databases, or other centralized administrative computingdevices that are typically placed in control rooms or other locationsaway from the harsher field environment of the plant, e.g., in aback-end environment of the process plant. Each of these hardwaredevices typically is centralized across the process plant or across aportion of the process plant. These hardware devices run applicationsthat may, for example, enable an operator to perform functions withrespect to controlling a process and/or operating the process plant,such as changing settings of the process control routine, modifying theoperation of the control modules within the controllers or the fielddevices, viewing the current state of the process, viewing alarmsgenerated by field devices and controllers, simulating the operation ofthe process for the purpose of training personnel or testing the processcontrol software, keeping and updating a configuration database, etc.The data highway utilized by the hardware devices, controllers and fielddevices may include a wired communication path, a wireless communicationpath, or a combination of wired and wireless communication paths.

As an example, the DeltaV™ control system, sold by Emerson ProcessManagement, includes multiple applications stored within and executed bydifferent devices located at diverse places within a process plant. Aconfiguration application, which resides in one or more workstations orcomputing devices in a back-end environment of a process control systemor plant, enables users to create or change process control modules anddownload these process control modules via a data highway to dedicateddistributed controllers. Typically, these control modules are made up ofcommunicatively interconnected function blocks, which are objects in anobject oriented programming protocol that perform functions within thecontrol scheme based on inputs thereto and that provide outputs to otherfunction blocks within the control scheme. The configuration applicationmay also allow a configuration designer to create or change operatorinterfaces which are used by a viewing application to display data to anoperator and to enable the operator to change settings, such as setpoints, within the process control routines. Each dedicated controllerand, in some cases, one or more field devices, stores and executes arespective controller application that runs the control modules assignedand downloaded thereto to implement actual process controlfunctionality. The viewing applications, which may be executed on one ormore operator workstations (or on one or more remote computing devicesin communicative connection with the operator workstations and the datahighway), receive data from the controller application via the datahighway and display this data to process control system designers,operators, or users using the user interfaces, and may provide any of anumber of different views, such as an operator's view, an engineer'sview, a technician's view, etc. A data historian application istypically stored in and executed by a data historian device thatcollects and stores some or all of the data provided across the datahighway while a configuration database application may run in a stillfurther computer attached to the data highway to store the currentprocess control routine configuration and data associated therewith.Alternatively, the configuration database may be located in the sameworkstation as the configuration application.

Generally, the commissioning of a process plant or system involvesbringing various components of the plant or system to the point wherethe system or plant can operate as intended. As is commonly known,physical process elements (such as valves, sensors, etc. that are to beutilized to control a process in a process plant) are installed atrespective locations within the field environment of the plant, e.g., inaccordance with Piping and Instrumentation Diagrams (P&IDs) and/or otherplans or “blueprints” of the plant floor layout and/or of the processlayout. After the process elements have been installed, at least some ofthe process elements are commissioned. For example, field devices,sampling points, and/or other elements are subject to beingcommissioned. Commissioning is an involved and complex process whichtypically includes multiple actions or activities. For example,commissioning may include actions or activities such as, among otherthings, verifying or confirming an identity of an installed processcontrol device (such as a field device) and its expected connections;determining and providing tags that uniquely identify the processcontrol device within the process control system or plant; setting orconfiguring initial values of parameters, limits, etc. for the device;verifying the correctness of the device's installation, operation andbehaviors under various conditions, e.g., by manipulating signalsprovided to the devices and performing other tests, and othercommissioning activities and actions. Device verification duringcommissioning is important for safety reasons, as well as to conform toregulatory and quality requirements.

Other commissioning actions or activities are performed on a processcontrol loop in which the device is included. Such commissioning actionsor activities include, for example, verifying that various signal sentacross the interconnection results in expected behavior at both ends ofthe interconnection, integrity checks on the process control loop,generating as-built I/O lists to indicate the actual physicalconnections of the devices that are implemented within the plant as wellas recording other “as-installed” data, to name a few.

For some commissioning tasks, a user may utilize a commissioning tool(e.g., a handheld or portable computing device) locally at varioustarget process control devices, components, and loops. Somecommissioning tasks may be performed at an operator interface of theprocess control system, e.g., at an operator interface of an operatorworkstation included in a back-end environment of the process plant.

Typically, the commissioning of a process plant requires physicaldevices, connections, wiring, etc. to be installed, set up, andinter-connected in the field environment of the process plant. At theback-end environment of the plant (e.g., at the centralizedadministrative computing devices such as operator workstations, personalcomputers or computing devices, centralized databases, configurationtools, etc. that are typically placed in control rooms or otherlocations away from the harsher field environment of the plant), datathat specifically identifies and/or addresses the various devices, theirconfigurations, and their interconnections is integrated, verified orcommissioned, and stored. As such, after the physical hardware has beeninstalled and configured, identification information, logicalinstructions, and other instructions and/or data is downloaded orotherwise provided to the various devices disposed in the fieldenvironment so that the various devices are able to communicate withother devices.

Of course, in addition to commissioning actions performed in theback-end environment, commissioning actions or activities are alsoperformed to verify the correctness of the connections and operations inthe field environment of both the physical and logical devices, bothindividually and integrally. For example, a field device may bephysically installed and individually verified, e.g., power-on,power-off, etc. A port of a field device may then be physicallyconnected to a commissioning tool via which simulated signals may besent to the field device, and the behavior of the field device inresponse to the various simulated signals may be tested. Similarly, afield device whose communication port is commissioned may eventually bephysically connected to a terminal block, and actual communicationsbetween the terminal block and the field device may be tested.Typically, commissioning of field devices and/or other components in thefield environment requires knowledge of component identifications, andin some cases, knowledge of component interconnections so that testsignals and responses can be communicated amongst field devices andother loop components and resultant behaviors verified. In currentlyknown commissioning techniques, such identification and interconnectionknowledge or data is generally provided to components in the fieldenvironment by the back-end environment. For example, the back-endenvironment will download field device tags that are used in controlmodules into the field devices that will be controlled by the controlmodules during live plant operations.

Coupling the field devices' communication ports to the terminal blockand, eventually, to the controllers in the back-end environment isgenerally a complex process. Field devices must be coupled to I/O cardsthat translate the signals received from the field devices to signalsthat can be processed by the controllers, and that translate the signalsreceived from the controllers to signals that can be processed by thefield devices. Each channel of each I/O card, corresponding to aparticular field device, must be associated with the appropriate signaltypes (so that signals are processed appropriately by the I/O card) andthe I/O card must be communicatively coupled to the controller orcontrollers that will eventually be receiving signals from and/orsending signals to the field devices coupled to that I/O card.

A termination block for a particular area typically serves as thetermination point for the wiring (or connection) of field devices from aparticular physical area of the process plant, which will be appreciatedis a significant amount of wiring in order to couple field devicesspread out over an area of a process control facility to thecorresponding termination block. A marshaling cabinet in the terminationarea includes a multiplicity of communication modules that marshal,organize or route signals between the communication modules coupled tothe field devices and one or more I/O cards communicatively coupled tothe controllers. In addition to the terminal blocks and communicationmodules, the marshaling cabinet also includes power provisioning tosupply power to the I/O cards and the communication modules, powerdissipation mechanisms (e.g., heat sinks, fans, etc.) to keep componentsin the marshaling cabinet from overheating, all of the wiring coming infrom the field devices, and various solutions for keeping that wiringfrom becoming too unwieldy.

SUMMARY

Techniques, systems, apparatuses, components, devices, and methods forimplementing distributed marshaling architectures in process controlplants are disclosed herein. Said techniques, systems, apparatuses,components, devices, and methods may apply to industrial process controlsystems, environments, and/or plants, which are interchangeably referredto herein as “industrial control,” “process control,” or “process”systems, environments, and/or plants. Typically, such systems and plantsprovide control, in a distributed manner, of one or more processes (alsoreferred to herein as “industrial processes”) that operate tomanufacture, refine, or transform, raw physical materials to generate orproduce products.

The distributed marshaling architectures include various techniques,systems, apparatuses, components, and/or methods that allow for at leastsome portions of the electronic marshaling (the communicative connectionof field devices to I/O cards to controllers) to be more widelydistributed than previous systems allowed. Distributed marshalingallows, for example, various portions of process control systems and/ortheir respective safety instrumented systems (SIS) (e.g., stand-alone orintegrated safety systems (ICSS)) to be communicatively coupled to I/Ocards and controllers with significantly shorter wiring runs, smallerpower provisioning requirements, fewer heat dissipation requirementsand, in general, greater flexibility.

For example, distributed marshaling allows field devices to becommunicatively coupled by short wiring runs to local marshaling modulesthat, in turn, are coupled via high speed networking connections to oneanother and to a head-end unit that is, in turn, coupled to I/O cardsand controllers. As such, a significant portion of local commissioningactivities of the physical components of the field environment may beeliminated, specifically as concerns the routing of long runs of wiringbetween a multiplicity of field devices, spread over a physical area ofthe process plant, and a centralized marshaling cabinet at which all ofthe wiring runs are terminated. The design and installation of powerprovisions and heat dissipation components for the centralizedmarshaling cabinets may likewise be eliminated.

A process control system operating to control a process in a processplant includes a plurality of process control field devices, aninput/output (I/O) card communicatively coupled to the plurality ofprocess control field devices, and a controller, communicatively coupledto the I/O card and receiving, via the I/O card, data from the pluralityof process control field devices, and operating to send, also via theI/O card, control signals to one or more of the process control fielddevices to control the operation of the process. The process controlsystem also includes a distributed marshaling module that includes apair of communication ports, one or more electronic marshaling componentslots, at least one electronic marshaling component slot having disposedtherein an electronic marshaling component, and a respective terminalblock corresponding to each of the one or more electronic marshalingcomponent slots, the terminal block for the at least one electronicmarshaling component slot being communicatively coupled to one of theplurality of field devices. A microprocessor, coupled to the pair ofcommunication ports is also included on the distributed marshalingmodule. The system further includes a head-end module. The head-endmodule has a first communication port coupling the head-end module tothe I/O card, a pair of second communication ports communicativelycoupled to the distributed marshaling module, a memory device havingstored thereon a database storing information received by themicroprocessor via the pair of second communication ports, and amicroprocessor coupled to the memory device. The microprocessor isconfigured to receive and transmit data via the pair of secondcommunication ports, store received data to the memory device, retrievedata from the memory device, and transmit retrieved data to thecontroller via the I/O card.

A distributed marshaling module for coupling field devices in a processplant to a controller in the process plant includes a pair ofcommunication ports. A first number of electronic marshaling componentslots is disposed on the distributed marshaling module which alsoincludes a second number, equal to the first number, of terminal blocks,each terminal block in communicative connection with one of theelectronic marshaling component slots and configured to becommunicatively connected to a respective one of the field devices.Still further, the distributed marshaling module includes a thirdnumber, less than or equal to the first number, of electronic marshalingcomponents disposed in the electronic marshaling component slots, eachof the electronic marshaling components configured to receive a signalfrom the respective one of the field devices and to convert the receivedsignal to a format compatible with an I/O card, and a microprocessorcoupled to the pair of communication ports.

A head-end module for coupling field devices in a process plant to acontroller in the process plant includes a first communication portcommunicatively connecting the head-end module to a first distributedmarshaling module, the first distributed marshaling module part of afirst ring architecture. A second communication port communicativelyconnecting the head-end module to a second distributed marshalingmodule, the second distributed marshaling module part of the first ringarchitecture, is also part of the head-end module. Further, the head-endmodule includes a third communication port communicatively connectingthe head-end module to an I/O card, the I/O card communicativelyconnected, in turn, to the controller. Further still, the head-endmodule includes a memory device and a microprocessor, coupled to thememory device. The microprocessor is configured to receive, via one orboth of the first and second communication ports, first data from fielddevices coupled to the first and second distributed marshaling modules,store the received first data to a database disposed in the memorydevice, retrieve the received first data from the database, transmit theretrieved first data to the controller via the I/O card, receive seconddata from the controller via the I/O card, and transmit, via one or bothof the first and second communication ports, the second data tospecified ones of the field devices.

A method of communicating data from a field device in a process plant toa controller in the process plant includes receiving from the fielddevice, at a terminal block, a signal representative of the data. Themethod further includes converting, in an electronic marshalingcomponent communicatively connected to the terminal block, the receivedsignal to a second signal, and registering the second signal from theelectronic marshaling component. The method also includes transmitting,from a microprocessor, to a head-end module remote from themicroprocessor and the electronic marshaling component, via either afirst communication port or a second communication port, a signalindicative of the registered second signal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a block diagram illustrating an example system processplant, at least a portion of which implement a distributed marshalingarchitecture as described herein;

FIG. 2A includes a block diagram of an example control loop which may beincluded in the process plant of FIG. 1 and which may be at leastpartially implemented using the distributed marshaling architecture;

FIG. 2B illustrates an example architecture of an electronic marshalingblock or apparatus which may be included in the process plant of FIG. 1;

FIG. 2C depicts a block diagram of an implementation of example loopswhich may be included in the process plant of FIG. 1 and which may be atleast partially commissioned utilizing the distributed marshalingarchitecture;

FIG. 2D depicts a block diagram of an another implementation of exampleloops which may be included in the process plant of FIG. 1 and which maybe at least partially commissioned utilizing the distributed marshalingarchitecture;

FIG. 2E depicts a block diagram of still another implementation ofexample loops which may be included in the process plant of FIG. 1 andwhich may be at least partially commissioned utilizing the distributedmarshaling architecture;

FIG. 2F depicts a block diagram depicting the connections variouselements of a control loop implementing the distributed marshalingarchitecture;

FIG. 2G is a block diagram illustrating several possible embodiments ofa distributed marshaling architecture;

FIG. 3 depicts a block diagram of an I/O head-end in accordance with anembodiment of a distributed marshaling architecture;

FIG. 4 depicts a block diagram of a distributed marshaling module inaccordance with embodiments of a distributed marshaling architecture;

FIG. 5 depicts an example distributed marshaling architecture that maybe implemented within the process control system of FIG. 1;

FIG. 6 depicts another example distributed marshaling architecture thatmay be implemented within the process control system of FIG. 1;

FIG. 7 depicts an still another embodiment of a distributed marshalingarchitecture that may be implemented; within the process control systemof FIG. 1;

FIG. 8 depicts a further embodiment of a distributed marshalingarchitecture that may be implemented; within the process control systemof FIG. 1;

FIG. 9 depicts an yet an additional embodiment of a distributedmarshaling architecture that may be implemented; within the processcontrol system of FIG. 1; and

FIG. 10 is a flow diagram depicting a method of communicating data froma field device to a controller in accordance with the describedembodiments.

DETAILED DESCRIPTION

As discussed above, a process plant, process control system, or processcontrol environment that, when on-line, operates to control one or moreindustrial processes in real-time may be communicatively connectedduring commissioning utilizing one or more of the novel techniques,systems, apparatuses, components, devices, and/or methods describedherein. The process plant, when commissioned and operating on-line,includes one or more wired or wireless process control devices,components, or elements that perform physical functions in concert witha process control system to control one or more processes executingwithin the process plant. The process plant and/or process controlsystem may include, for example, one or more wired communicationnetworks and/one or more wireless communication networks. Additionally,the process plant or control system may include centralized databases,such as continuous, batch, asset management, historian, and other typesof databases.

To illustrate, FIG. 1 is a block diagram of an example process plant,process control system, or process control environment 5, at least aportion of which has been commissioned by using any one or more of thetechniques and apparatuses described herein. The process plant 5includes one or more process controllers that receive signals indicativeof process measurements made by field devices, process this informationto implement a control routine, and generate control signals that aresent over wired or wireless process control communication links ornetworks to other field devices to control the operation of a process inthe plant 5. Typically, at least one field device performs a physicalfunction (e.g., opening or closing a valve, increasing or decreasing atemperature, taking a measurement, sensing a condition, etc.) to controlthe operation of a process. Some types of field devices communicate withcontrollers by using I/O devices. Process controllers, field devices,and I/O devices may be wired or wireless, and any number and combinationof wired and wireless process controllers, field devices and I/O devicesmay be included in the process plant environment or system 5.

For example, FIG. 1 illustrates a process controller 11 that iscommunicatively connected to wired field devices 15-22 via input/output(I/O) cards 26 and 28, and to wired field devices 23 a-c and 24 a-c byan I/O card 31 communicatively connected to a head-end unit 29. Thecontroller 11 is communicatively connected to wireless field devices40-46 via a wireless gateway 35 and a process control data highway orbackbone 10. The process control data highway 10 may include one or morewired and/or wireless communication links, and may be implemented usingany desired or suitable or communication protocol such as, for example,an Ethernet protocol. In some configurations (not shown), the controller11 may be communicatively connected to the wireless gateway 35 using oneor more communications networks other than the backbone 10, such as byusing any number of other wired or wireless communication links thatsupport one or more communication protocols, e.g., Wi-Fi or other IEEE802.11 compliant wireless local area network protocol, mobilecommunication protocol (e.g., WiMAX, LTE, or other ITU-R compatibleprotocol), Bluetooth®, HART®, WirelessHART®, Profibus, FOUNDATION®Fieldbus, etc.

The controller 11, which may be, by way of example, the DeltaV™controller sold by Emerson Process Management, may operate to implementa batch process or a continuous process using at least some of the fielddevices 15-22 and 40-46. In an embodiment, in addition to beingcommunicatively connected to the process control data highway 10, thecontroller 11 is also communicatively connected to at least some of thefield devices 15-22 and 40-46 using any desired hardware and softwareassociated with, for example, standard 4-20 mA devices, I/O cards 26,28, and/or any smart communication protocol such as the FOUNDATION®Fieldbus protocol, the HART® protocol, the WirelessHART® protocol, etc.In FIG. 1, the controller 11, the field devices 15-22 and the I/O cards26, 28 are wired devices, and the field devices 40-46 are wireless fielddevices. Of course, the wired field devices 15-22 and wireless fielddevices 40-46 could conform to any other desired standard(s) orprotocols, such as any wired or wireless protocols, including anystandards or protocols developed in the future.

The process controller 11 of FIG. 1 includes a processor 30 thatimplements or oversees one or more process control routines 38 (e.g.,that are stored in a memory 32). The processor 30 is configured tocommunicate with the field devices 15-22 and 40-46 and with other nodescommunicatively connected to the controller 11. It should be noted thatany control routines or modules described herein may have parts thereofimplemented or executed by different controllers or other devices if sodesired. Likewise, the control routines or modules 38 described hereinwhich are to be implemented within the process control system 5 may takeany form, including software, firmware, hardware, etc. Control routinesmay be implemented in any desired software format, such as using objectoriented programming, ladder logic, sequential function charts, functionblock diagrams, or using any other software programming language ordesign paradigm. The control routines 38 may be stored in any desiredtype of memory 32, such as random access memory (RAM), or read onlymemory (ROM). Likewise, the control routines 38 may be hard-coded into,for example, one or more EPROMs, EEPROMs, application specificintegrated circuits (ASICs), or any other hardware or firmware elements.Thus, the controller 11 may be configured to implement a controlstrategy or control routine in any desired manner.

The controller 11 implements a control strategy using what are commonlyreferred to as function blocks, where each function block is an objector other part (e.g., a subroutine) of an overall control routine andoperates in conjunction with other function blocks (via communicationscalled links) to implement process control loops within the processcontrol system 5. Control based function blocks typically perform one ofan input function, such as that associated with a transmitter, a sensoror other process parameter measurement device, a control function, suchas that associated with a control routine that performs PID, fuzzylogic, etc. control, or an output function which controls the operationof some device, such as a valve, to perform some physical functionwithin the process control system 5. Of course, hybrid and other typesof function blocks exist. Function blocks may be stored in and executedby the controller 11, which is typically the case when these functionblocks are used for, or are associated with standard 4-20 mA devices andsome types of smart field devices such as HART® devices, or may bestored in and implemented by the field devices themselves, which can bethe case with FOUNDATION® Fieldbus devices. The controller 11 mayinclude one or more control routines 38 that may implement one or morecontrol loops, which are performed by executing one or more of thefunction blocks.

The wired field devices 15-22 may be any types of devices, such assensors, valves, transmitters, positioners, etc., while the I/O cards 26and 28 may be any types of I/O devices conforming to any desiredcommunication or controller protocol. In FIG. 1, the field devices 15-18are standard 4-20 mA devices or HART® devices that communicate overanalog lines or combined analog and digital lines to the I/O card 26,while the field devices 19-22 are smart devices, such as FOUNDATION®Fieldbus field devices, that communicate over a digital bus to the I/Ocard 28 using a FOUNDATION® Fieldbus communications protocol. In someembodiments, though, at least some of the wired field devices 15, 16 and18-21 and/or at least some of the I/O cards 26, 28 additionally oralternatively communicate with the controller 11 using the processcontrol data highway 10 and/or by using other suitable control systemprotocols (e.g., Profibus, DeviceNet, Foundation Fieldbus, ControlNet,Modbus, HART, etc.).

At the same time, the wired field devices 23 a-c and 24 a-c may be anytypes of devices, including sensors, valves, transmitters, positioners,etc., and may communicate, using analog and/or digital signals, with theI/O card 31, which, as will be described, may be coupled to any type offield device by an electronic marshaling component (not depicted inFIG. 1) that converts signals between those used by the field device,and those compatible with the I/O card 31. Each of the field devices 23a-23 c is coupled to a local distributed marshaling module 25, whileeach of the field devices 24 a-24 c is coupled to a local distributedmarshaling module 27. The distributed marshaling modules 25, 27 carry anelectronic marshaling component for each of the field devices 23 a-c, 24a-c coupled to the respective distributed marshaling module. While eachof the distributed marshaling modules 25, 27 is depicted in FIG. 1 ashaving three field devices 23 a-c, 24 a-c coupled to it, it will beapparent through the remainder of the description that each of thedistributed marshaling modules 25, 27 may carry any number of electronicmarshaling components supporting any number of corresponding fielddevices. The distributed marshaling modules 25, 27 communicate with thehead-end unit 29 via a network 33 having a ring architecture, thehead-end unit 29 conveying data to the I/O card 31 and, ultimately, tothe controller 11.

In FIG. 1, the wireless field devices 40-46 communicate via a wirelessprocess control communication network 70 using a wireless protocol, suchas the WirelessHART® protocol. Such wireless field devices 40-46 maydirectly communicate with one or more other devices or nodes of thewireless network 70 that are also configured to communicate wirelessly(using the wireless protocol or another wireless protocol, for example).To communicate with one or more other nodes that are not configured tocommunicate wirelessly, the wireless field devices 40-46 may utilize awireless gateway 35 connected to the process control data highway 10 orto another process control communications network. The wireless gateway35 provides access to various wireless devices 40-58 of the wirelesscommunications network 70. In particular, the wireless gateway 35provides communicative coupling between the wireless devices 40-58, thewired devices 11-28, and/or other nodes or devices of the processcontrol plant 5. For example, the wireless gateway 35 may providecommunicative coupling by using the process control data highway 10and/or by using one or more other communications networks of the processplant 5.

Similar to the wired field devices 15-22, the wireless field devices40-46 of the wireless network 70 perform physical control functionswithin the process plant 5, e.g., opening or closing valves, or takingmeasurements of process parameters. The wireless field devices 40-46,however, are configured to communicate using the wireless protocol ofthe network 70. As such, the wireless field devices 40-46, the wirelessgateway 35, and other wireless nodes 52-58 of the wireless network 70are producers and consumers of wireless communication packets.

In some configurations of the process plant 5, the wireless network 70includes non-wireless devices. For example, in FIG. 1, a field device 48of FIG. 1 is a legacy 4-20 mA device and a field device 50 is a wiredHART® device. To communicate within the network 70, the field devices 48and 50 are connected to the wireless communications network 70 via awireless adaptor 52 a, 52 b. The wireless adaptors 52 a, 52 b support awireless protocol, such as WirelessHART, and may also support one ormore other communication protocols such as Foundation® Fieldbus,PROFIBUS, DeviceNet, etc. Additionally, in some configurations, thewireless network 70 includes one or more network access points 55 a, 55b, which may be separate physical devices in wired communication withthe wireless gateway 35 or may be provided with the wireless gateway 35as an integral device. The wireless network 70 may also include one ormore routers 58 to forward packets from one wireless device to anotherwireless device within the wireless communications network 70. In FIG.1, the wireless devices 40-46 and 52-58 communicate with each other andwith the wireless gateway 35 over wireless links 60 of the wirelesscommunications network 70, and/or via the process control data highway10.

In FIG. 1, the process control system 5 includes one or more operatorworkstations 71 that are communicatively connected to the data highway10. Via the operator workstations 71, operators may view and monitorrun-time operations of the process plant 5, as well as take anydiagnostic, corrective, maintenance, and/or other actions that may berequired. At least some of the operator workstations 71 may be locatedat various, protected areas in or near the plant 5, and in somesituations, at least some of the operator workstations 71 may beremotely located, but nonetheless in communicative connection with theplant 5. Operator workstations 71 may be wired or wireless computingdevices.

The example process control system 5 is further illustrated as includinga configuration application 72 a and configuration database 72 b, eachof which is also communicatively connected to the data highway 10. Asdiscussed above, various instances of the configuration application 72 amay execute on one or more computing devices (not shown) to enable usersto create or change process control modules and download these modulesvia the data highway 10 to the controllers 11, as well as enable usersto create or change operator interfaces via which in operator is able toview data and change data settings within process control routines. Theconfiguration database 72 b stores the created (e.g., configured)modules and/or operator interfaces. Generally, the configurationapplication 72 a and configuration database 72 b are centralized andhave a unitary logical appearance to the process control system 5,although multiple instances of the configuration application 72 a mayexecute simultaneously within the process control system 5, and theconfiguration database 72 b may be implemented across multiple physicaldata storage devices. Accordingly, the configuration application 72 a,configuration database 72 b, and user interfaces thereto (not shown)comprise a configuration or development system 72 for control and/ordisplay modules. Typically, but not necessarily, the user interfaces forthe configuration system 72 are different than the operator workstations71, as the user interfaces for the configuration system 72 are utilizedby configuration and development engineers irrespective of whether ornot the plant 5 is operating in real-time, whereas the operatorworkstations 71 are utilized by operators during real-time operations ofthe process plant 5 (also referred to interchangeably here as “run-time”operations of the process plant 5).

The example process control system 5 includes a data historianapplication 73 a and data historian database 73 b, each of which is alsocommunicatively connected to the data highway 10. The data historianapplication 73 a operates to collect some or all of the data providedacross the data highway 10, and to historize or store the data in thehistorian database 73 b for long term storage. Similar to theconfiguration application 72 a and configuration database 72 b, the datahistorian application 73 a and historian database 73 b are centralizedand have a unitary logical appearance to the process control system 5,although multiple instances of a data historian application 73 a mayexecute simultaneously within the process control system 5, and the datahistorian 73 b may be implemented across multiple physical data storagedevices.

In some configurations, the process control system 5 includes one ormore other wireless access points 74 that communicate with other devicesusing other wireless protocols, such as Wi-Fi or other IEEE 802.11compliant wireless local area network protocols, mobile communicationprotocols such as WiMAX (Worldwide Interoperability for MicrowaveAccess), LTE (Long Term Evolution) or other ITU-R (InternationalTelecommunication Union Radiocommunication Sector) compatible protocols,short-wavelength radio communications such as near field communications(NFC) and Bluetooth, or other wireless communication protocols.Typically, such wireless access points 74 allow handheld or otherportable computing devices (e.g., user interface devices 75) tocommunicate over a respective wireless process control communicationnetwork that is different from the wireless network 70 and that supportsa different wireless protocol than the wireless network 70. For example,a wireless or portable user interface device 75 may be a mobileworkstation or diagnostic test equipment that is utilized by an operatorwithin the process plant 5 (e.g., an instance of one of the operatorworkstations 71). In some scenarios, in addition to portable computingdevices, one or more process control devices (e.g., controller 11, fielddevices 15-22, or wireless devices 35, 40-58) also communicate using thewireless protocol supported by the access points 74.

In some configurations, the process control system 5 includes one ormore gateways 76, 78 to systems that are external to the immediateprocess control system 5. Typically, such systems are customers orsuppliers of information generated or operated on by the process controlsystem 5. For example, the process control plant 5 may include a gatewaynode 76 to communicatively connect the immediate process plant 5 withanother process plant. Additionally or alternatively, the processcontrol plant 5 may include a gateway node 78 to communicatively connectthe immediate process plant 5 with an external public or private system,such as a laboratory system (e.g., Laboratory Information ManagementSystem or LIMS), an operator rounds database, a materials handlingsystem, a maintenance management system, a product inventory controlsystem, a production scheduling system, a weather data system, ashipping and handling system, a packaging system, the Internet, anotherprovider's process control system, or other external systems.

It is noted that although FIG. 1 only illustrates a single controller 11with a finite number of field devices 15-22 and 40-46, wireless gateways35, wireless adaptors 52, access points 55, routers 58, and wirelessprocess control communications networks 70 included in the exampleprocess plant 5, this is only an illustrative and non-limitingembodiment. Any number of controllers 11 may be included in the processcontrol plant or system 5, and any of the controllers 11 may communicatewith any number of wired or wireless devices and networks 15-22, 40-46,35, 52, 55, 58 and 70 to control a process in the plant 5. For example,the process plant 5 may include various physical areas, each having anassociated one or more controllers 11 in communication (via additionalI/O cards 26, 28) with an associated set of field devices and networks15-22, 40-46, 35, 52, 55, 58 and 70 in that physical area.

Further, it is noted that the process plant or control system 5 of FIG.1 includes a field environment 122 (e.g., “the process plant floor 122”)and a back-end environment 125 which are communicatively connected bythe data highway 10. As shown in FIG. 1, the field environment 122includes physical components (e.g., process control devices, networks,network elements, etc.) that are disposed, installed, and interconnectedtherein to operate to control the process during run-time. For example,the controller 11, the I/O cards 26,28, the field devices 15-22, andother devices and network components 40-46, 35, 52, 55, 58 and 70 arelocated, disposed, or otherwise included in the field environment 122 ofthe process plant 5. Generally speaking, in the field environment 122 ofthe process plant 5, raw materials are received and processed using thephysical components disposed therein to generate one or more products.

The back-end environment 125 of the process plant 5 includes variouscomponents such as computing devices, operator workstations, databasesor databanks, etc. that are shielded and/or protected from the harshconditions and materials of the field environment 122. Referring to FIG.1, the back-end environment 125 includes, for example, the operatorworkstations 71, the configuration or development systems 72 for controlmodules and other executable modules, data historian systems 73, and/orother centralized administrative systems, computing devices, and/orfunctionality that support the run-time operations of the process plant5. In some configurations, various computing devices, databases, andother components and equipment included in the back-end environment 125of the process plant 5 may be physically located at different physicallocations, some of which may be local to the process plant 5, and someof which may be remote.

FIGS. 2A to 2G generally describe the non-distributed portions of thecommunication architecture, corresponding to the I/O cards 26, 28, andthe field devices 15-22, though the concepts described with respect toFIGS. 2A to 2G are, in large part, extendible to the distributed portionof the architecture, as will later be apparent. FIG. 2A includes a blockdiagram depicting an example architecture of an example process controlloop 100 a in which a smart or intelligent field device 102 a isincluded, and that may be commissioned using any one or more of thetechniques described herein. Generally, as used herein, “smart” or“intelligent” field devices are field devices that integrally includeone or more processors and one or more memories. On the other hand, asused herein, “dumb” or “legacy” field devices do not include on-boardprocessor(s) and/or on-board memories.

The loop 100 a may be integrated or incorporated into a process plant tobe utilized in controlling a process therein during run-time operationsof the process plant. For example, the loop 100 a may be installed ordisposed in the field environment 122 of the process plant 5.

Within the example process control loop 100 a shown in FIG. 2A, a smartor intelligent field device 102 a is communicatively connected (e.g., ina wired or wireless manner) to an electronic marshaling device orcomponent (EMC) 110 a (e.g., a CHARacterization Module or CHARM providedby Emerson Process Management). The EMC 110 a is communicativelyconnected 112 a to an I/O terminal block 105 a that, in turn, iscommunicatively connected to an I/O card 108 a. The I/O card 108 a iscommunicatively connected 118 a to a controller 120 a, which, in turn,is communicatively connected 121 a to the back-end environment 125 ofthe process plant 5. During on-line operations of the process plant 5,the process controller 120 a receives digital values of the signalsgenerated by the smart field device 102 a and operates on the receivedvalues to control a process within the plant 5, and/or sends signals tochange the operation of the field device 102 a. Additionally, thecontroller 120 a may send information to and receive information fromthe back-end environment 125 via the communicative connection 121 a.

In FIG. 2A, the electronic marshaling component 110 a, the I/O terminalblock 105 a, and the I/O card 108 a are depicted as being locatedtogether in a cabinet or housing 115 a (such as an I/O cabinet) thatelectrically interconnects the electronic marshaling component 110 a,the I/O terminal block 105 a, and the I/O card 108 a and/or othercomponents housed within the cabinet 115 a via a bus, backplane, orother suitable interconnection mechanism. Of course, the housing of theelectronic marshaling component 110 a, the I/O terminal block 105 a, andthe I/O card 108 a in the cabinet 115 a as depicted in FIG. 2A is onlyone of many housing configurations possible.

With particular regard to the electronics marshaling component 110 a,FIG. 2B illustrates a perspective view of an example electronicmarshaling block or apparatus 140 that supports the EMC 110 a shown inFIG. 2A, and thus is discussed below with simultaneous reference to FIG.2A. In FIG. 2B, the electronic marshaling block or apparatus 140includes an I/O card carrier 142 that supports one or more EMC I/O cards145 to which the process controller 120 a may be connected (e.g., viathe wired or wireless connection 118 a shown in FIG. 2A). Additionally,the electronic marshaling block or apparatus 140 includes one or moreelectronic marshaling modules 148 that communicatively connect to theI/O card carrier 142 (and therefore, to the EMC I/O cards 145), and thatsupport a plurality of individually configurable channels. Each channelcorresponds to a dedicated terminal of the EMC terminal block 150,coupled to an EMC slot 149 a into which the EMC 110 a may be securelyreceived and electronically connected, thereby electronically marshalingthe field device 102 a and the I/O card 108 a with the controller 120 a.For instance, the I/O terminal block 105 a is the EMC terminal block 150coupled to the EMC slot 149 a into which the EMCs 110 a and 152 arereceived, and the I/O card 108 a is the EMC I/O card 145 correspondingto the EMC terminal block 150 and to which the controller 120 a isconnected 118 a. FIG. 2B also shows other EMCs 152 which have beenreceived by their respective EMC terminal blocks 150, and which may beconnected to other respective devices in the field environment 122 ofthe process plant 5 (not shown).

As depicted in FIG. 2B, in embodiments a pair of redundant I/O cards 145(e.g., a primary I/O card 108 a and a secondary I/O card 108 a′) isfitted to provide fault tolerant operations in the event that one of theredundant I/O cards 108 a, 108 a′ fails. In the event of such a failure,for example the failure of the primary I/O card 108 a, the remaining oneof the redundant I/O cards 108 a, 108 a′ (e.g., the secondary I/O card108 a′) assumes control and performs the same operations that wouldotherwise have been performed by the failed I/O card.

As should be apparent with reference to FIG. 2B, each electronicmarshaling module 148 supports a plurality of configurable channels,each of which corresponds to an individual EMC. Such a configuration isdepicted in FIG. 2C. FIG. 2C depicts a multiplicity of field devices 102a-102 l. Each of the field devices 102 a-102 l is communicativelyconnected (e.g., in a wired or wireless manner) to a correspondingelectronic marshaling component 110 a-110 l. Each of the electronicmarshaling components 110 a-110 l is communicatively connected 112 a-112l to the same I/O terminal block (just as the EMC 110 a and the otherEMCs 152 are all coupled to the terminal block 150 in FIG. 2B) that, inturn, is communicatively coupled to redundant I/O cards 108 a, 108 a′.The redundant I/O cards 108 a, 108 a′ are communicatively connected 118a to the controller 120 a, which, in turn, is communicatively connected121 a to the back-end environment 125 of the process plant 5. Theelectronic marshaling components 110 a-l, the I/O terminal block 150,and the redundant I/O cards 108 a, 108 a′ may all be enclosed in thecabinet 115 a. While in the embodiment depicted in FIG. 2C, the I/Oterminal block 105 a supports 12 electronic marshaling components (e.g.,110 a-l), the I/O terminal block 105 a may, in varying embodiments,support fewer or more electronic marshaling components. Additionally,fewer electronic marshaling components could be connected to the I/Oterminal block 105 a than the I/O terminal block 105 a supports. Forexample, the I/O terminal block 105 a may support 16 electronicmarshaling components, but at a particular time may be connected to 15,12, 10, 7, or even 1 electronic marshaling component(s).

FIG. 2D depicts another embodiment. While not immediately apparent fromFIG. 2B, each of the I/O card carriers 142 may support multiple ones ofthe electronic marshaling modules 148 with EMC terminal blocks 150, inorder to provide support for additional I/O channels. FIG. 2D depicts afirst multiplicity of field devices 102 a-102 land a second multiplicityof field devices 102 m-102 x. Each of the field devices 102 a-102 x iscommunicatively connected (e.g., in a wired or wireless manner) to acorresponding electronic marshaling component 110 a-110 x. Each of theelectronic marshaling components 110 a-110 l, corresponding to the firstmultiplicity of field devices 102 a-102 l, is communicatively connected112 a-112 lto a first I/O terminal block 105 a. At the same time, eachof the electronic marshaling components 110 m-110 x, corresponding tothe second multiplicity of field devices 102 m-102 x, is communicativelyconnected 112 m-112 x to a second I/O terminal block 105 b. Each of thefirst and second I/O terminal blocks 105 a and 105 b is, in turn, iscommunicatively coupled to the redundant I/O cards 108 a, 108 a′. Theredundant I/O-cards 108 a, 108 a′ are communicatively connected 118 a tothe controller 120 a, which, in turn, is communicatively connected 121 ato the back-end environment 125 of the process plant 5. The electronicmarshaling components 110 a-x, the I/O terminal blocks 105 a and 105 b,and the redundant I/O cards 108 a, 108 a′ may all be enclosed in thecabinet 115 a. While in the embodiment depicted in FIG. 2D, each of theI/O terminal blocks 105 a and 105 b supports 12 electronic marshalingcomponents (e.g., 110 a-l), the I/O terminal blocks 105 a and 105 b may,in varying embodiments, support fewer or more electronic marshalingcomponents, as was the case in the embodiment depicted in FIG. 2C.

Additionally, while FIG. 2D depicts two I/O terminal blocks 105 a and105 b coupled to a pair of redundant I/O cards 108 a, 108 a′, in variousembodiments, each I/O card (and thus, each pair of redundant I/O cards)may support fewer or more I/O terminal blocks and/or fewer or more totalI/O channels. For example, in a particular embodiment, each I/O card 108supports a total of up to 96 I/O channels, which corresponds to eightI/O terminal blocks 105 if each terminal block supports 12 electronicmarshaling components 110.

FIG. 2E depicts yet another embodiment, this one illustrating thecommunicative connection between field devices and multiple controllers.FIG. 2E depicts the first multiplicity of field devices 102 a-102 landthe second multiplicity of field devices 102 m-102 x. As in each ofFIGS. 2C and 2D, each of the field devices 102 a-102 x iscommunicatively connected (e.g., in a wired or wireless manner) to acorresponding electronic marshaling component 110 a-110 x. However, inthe embodiment depicted in FIG. 2E, each of the electronic marshalingcomponents 110 a-110 l, corresponding to the first multiplicity of fielddevices 102 a-102 l, is communicatively connected 112 a-112 l to a firstI/O terminal block 105 a that, in turn, is communicatively connected tothe first pair of redundant I/O cards 108 a, 108 a′. At the same time,each of the electronic marshaling components 110 m-110 x, correspondingto the second multiplicity of field devices 102 m-102 x, iscommunicatively connected 112 m-112 x to the second I/O terminal block105 b that, in turn, is communicatively connected to a second pair ofredundant I/O cards 108 b, 108 b′. The redundant I/O-cards 108 a, 108 a′are communicatively connected 118 a to the controller 120 a, while theredundant I/O cards 108 b, 108 b′ are communicatively connected 118 b toa controller 120 b. The controllers 120 a, 120 b are, in turn,communicatively connected 121 a, 121 b to the back-end environment 125of the process plant 5. As depicted, the first multiplicity ofelectronic marshaling components 110 a-110 l, the I/O terminal block 105a, and the redundant I/O cards 108 a, 108 a′ are enclosed in the cabinet115 a, while the second multiplicity of electronic marshaling components110 m-110 x, the I/O terminal block 105 b, and the redundant I/O cards108 b, 108 b′ are enclosed in a cabinet 115 b. Of course, it will beappreciated that the contents depicted in cabinets 115 a and 115 b may,in some embodiments, be in a single cabinet.

Turning now to FIG. 2F, the control loop 100 a (see FIG. 2A) is depictedin greater detail, illustrating a particular benefit duringconfiguration and commissioning of the process plant 5. With referencebriefly to FIG. 2B, the EMC terminal block 150 includes, for eachchannel on the electronic marshaling module 148, a set of terminals 151a-151 d. Though illustrated as including four terminals 151 a-151 d,each channel of the EMC terminal block 150 may include two or threeterminals in other embodiments. In the embodiment illustrated in FIG.2F, each channel of the EMC terminal block 150 includes four terminals151 a-151 d, so that each channel may support devices having one, two,three, or four-wire connections to its respective field device 102 a.

The field device 102 a is coupled to some or all of the terminals 151a-151 d by a wire run 153, that originates at the field device 102 a andterminates at the terminals 151 a-151 d. In embodiments, the wire run153 may be several, tens, or even hundreds of feet long, depending onthe location of the field device 102 a relative to the cabinet 115 a,the type of signals carried by the wire run 153, the specific path ofthe wire run 153 around the process plant 5, etc. In some embodiments,the wire run 153 may be between a receiver receiving signals from thefield device 102 a (or from a multiplicity of field devices) and theterminals 151 a-151 d.

As will be understood, the number of wires that terminate at theterminals 151 a-151 d of a given channel will depend upon the type offield device coupled to the terminals 151 a-151 d, as well as on thetransmission protocol implemented by the field device 102 a and on thesignal type. A defining characteristic of process plants that implementthe EMC architecture (i.e., that use EMC I/O cards, EMCs, etc.) is thatthe field devices coupled to the EMC I/O cards may be coupled to anychannel on the EMC terminal block 150 without regard to the type ofsignal being communicated, via the I/O card and the EMC, between thecontroller and the field device. This is because the EMC functions toconvert the signal on the field device side to a signal that can becommunicated to the controller, and vice versa. This is in contrast withprevious architectures in which each I/O card had channels dedicated toparticular types of signals, requiring the field devices to be wired tothe terminals corresponding to the correct channels on the I/O card.

Referring again to FIG. 2F, the signals on the various wires of thewiring run 153 are passed via connections (e.g., the connection 112 a inprevious figures) to the EMC 110 a by the electronic marshaling module148. That is, the electronic marshaling module 148 serves as a backplaneconnection between the terminals 151 a-151 d on the EMC terminal block150 and the EMC 110 a inserted into the EMC slot 149 a. The EMC 110 a isselected according to the signals that will be transmitted on the wiringrun 153 that terminates at the corresponding set of terminals 151 a-151d. For instance, if the field device 102 a is sending signals thatrepresent an Analog Input (AI), then the EMC 110 a selected to beinserted into the corresponding EMC slot 149 a would be an AI EMC, andwould convert the analog signal (e.g., 4-20 mA) to a correspondingdigital signal for the I/O card 108 a to communicate to the controller120 a. As another example, if the field device 102 a is receiving aDiscrete Output (DO) signal from the controller 120 a, then the EMC 110a selected to be inserted into the corresponding EMC slot 149 a would bea DO EMC. The EMC 110 a is configured to convert the signals received atthe terminals 151 a-151 d to signals that can be passed to thecontroller 120 a by the I/O card 108, and/or to convert the signalsreceived from the controller 120 a via the I/O card 108 to signals thatcan be passed to the field device 102 a across the wiring run 153.

FIG. 2G is a block diagram for the purposes of illustrating anddescribing several possible embodiments. In FIG. 2G, 12 field devices102 a-102 l are each coupled by respective wire runs 153 a-153 l torespective terminals 150 a-150 l on an electronic marshaling module 148.The electronic marshaling module 148 communicatively connects, as abackplane, the terminals 150 a-150 l (and the field devices 102 a-102 lcommunicatively connected to them) to respective EMC slots 149 a-149 l.Each of the EMC slots 149 a-149 l is populated with a respective EMC 110a-110 l, selected according to the signals being communicated to/fromits respective field device 102 a-102 l. The electronic marshalingmodule 148 is communicatively connected to an I/O card carrier 142, suchthat each of the channels corresponding to the EMC slots 149 a-149 l iscommunicatively connected to a respective channel on each of a pair ofredundant I/O cards 108 a, 108 a′ populating the I/O card carrier 142.The I/O card carrier 142 is coupled to a controller 120 a via aconnection 118 a, thereby providing a communicative connection betweenthe controller 120 a and each of the redundant I/O cards 108 a, 108 a′.

FIG. 2G also depicts several memory devices at various locations betweenthe controller 120 a and the field devices 102 a-102 l. Each of theseveral memory devices represents a possible location where data couldbe stored when received from the field devices 102 a-102 l before beingsent to the controller 120 a, or when received from the controller 120 abefore being sent to the field devices 102 a-102 l. In an embodiment,data received from each of the field devices 102 a-102 l is transmittedto the respective EMCs 110 a-110 l, and directly to the redundant I/Ocards 108 a, 108 a′, where it is stored until needed (e.g., untilrequested by the controller 120 a, or until an assigned time slot duringwhich the data on a particular channel are to be transmitted to thecontroller 120 a) on memory devices 164 and 162, respectively. Inanother embodiment, data received from each of the field devices 102a-102 l is transmitted to the respective EMCs 110 a-110 l, and directlyto a memory device 160 disposed on or in the I/O card carrier 142, whereit is stored until needed (e.g., until requested by the controller 120a, or until an assigned time slot during which the data on a particularchannel are to be transmitted to the controller 120 a) and thenretrieved by the redundant I/O cards 108 a, 108 a′ and transmitted tothe controller 120 a. In still another embodiment, data received fromeach of the field devices 102 a-102 l is transmitted to the respectiveEMCs 110 a-110 l, and stored in respective memory devices 166 a-166 ldisposed in or associated with the EMC slots 149 a-149 l. The data maybe stored in the memory devices 166 a-166 l until the redundant I/Ocards 108 a, 108 a′ retrieve the data for transmission to the controller120 a. In a fourth embodiment, data received from each of the fielddevices 102 a-102 l is transmitted to the respective EMCs 110 a-110 l,and stored in respective memory devices 168 a-168 l disposed within theEMCs 110 a-110 l. The data may be stored in the memory devices 168 a-168l until the redundant I/O cards 108 a, 108 a′ retrieve the data fortransmission to the controller 120 a. In yet another embodiment, datareceived from each of the field devices 102 a-102 l is transmitted tothe respective EMCs 110 a-110 l, and stored in a memory device 170disposed in the electronic marshaling module 148. The data may be storedin the memory device 170 until the redundant I/O cards 108 a, 108 a′retrieve the data for transmission to the controller 120 a.

Of course, in various embodiments, the memory devices 160, 162, 164, 166a-166 l, 168 a-168 l, and/or 170 may be used in combination, with databeing stored in multiple places. Additionally, in embodiments, the datamay be updated in the memory or memories more or less frequently thanthe data are transmitted to the controller 120 a. That is, while thememory or memories may be storing only a single value for each parameterat a given time, the value may be retrieved more frequently than it isupdated, or may be updated multiple times before it is retrieved.

In still other embodiments, a scanning module 172 operates on theelectronic marshaling module 148 to scan repeatedly (e.g., periodically)each of the populated EMC slots 149 a-149 l and to store the data fromeach of the EMCs 110 a-110 l in the populated EMC slots 149 a-149 l toone or more of the memory devices and, for example, the memory devices170, 160, 162, and/or 164. The scanning module may be, for instance, amultiplexing device scanning the values presently output by each of theEMCs 110 a-110 l at any given point. Alternatively, the scanning module172 may be scanning the memory devices associated with the EMCs 110a-110 l, such as the memory devices 166 a-166 l, or the memory devices168 a-168 l. Simply put, the scanning module 172 may be implemented toscan the data output directly by the EMCs 110 a-110 l, or may beimplemented to scan the data stored in a set of memory devices.

FIGS. 3 through 6 illustrate the distributed marshaling features of theprocess plant 5 that provide a number of additional advantages whenimplemented in the process plant 5. Specifically, while some portions ofthe process plant 5 may include centralized marshaling cabinets asdescribed with respect to FIGS. 2A to 2G (e.g., the cabinet 115 adepicted in FIG. 2A), in which a marshaling block 140, includes one ormore I/O card carriers 142 each coupled to one or more electronicmarshaling modules 148 with respective EMCs 152, the presently describedprocess plant 5 may also include distributed EMC networks that do notcentralize all of the components of the marshaling block 140 in a singlecabinet or location. Instead, the I/O card carrier 142 may be located inone place (e.g., in the marshaling cabinet 115 a), while EMCs 152 andsupporting architecture (as will be described) may be remotely locatedfrom the I/O card carrier 142 and distributed throughout the fieldenvironment 122 of the process plant 5.

As will be evident from the description to follow, the benefits of suchan arrangement include: shorter wiring runs between the field devicesand the terminal blocks; smaller power requirements in each location;lower heat dissipation requirements in each location; greater redundancyfor communications; and others.

FIG. 3 depicts a block diagram of a I/O head-end 200 in such adistributed system. The head-end 200 performs many of the same functionsas the I/O card carrier 142 depicted in FIG. 2B, namely, the head-end200 carries (and is communicatively connected to) a pair of redundantI/O cards 202, 202′ that communicate both with field devices and withone or more controllers, as described above. Each of the I/O cards 202,202′ may include a respective memory device 203, 203′ that may storecomputer-readable instructions for operating the I/O cards 202, 202′,and/or may temporarily store data being communicated to one or morefield devices from a controller, or to a controller from one or morefield devices. Additionally, or alternatively, a memory device 208 maystore computer-readable instructions for operating the I/O cards 202,202′, for coordinating redundancy between the I/O cards 202, 202′, forcoordinating communications between the head-end 200 and other devicesconnected thereto (as described below) and/or may temporarily store(e.g., in a database) data being communicated to one or more fielddevices from a controller, or to a controller from one or more fielddevices. Lastly, a processor 205 may be coupled to the memory device 208and may execute the computer-readable instructions stored thereon forthe purpose of storing and/or retrieving data from the memory device208, controlling the I/O cards 202, 202′, and communicating via avariety of communication ports.

A communication port 207, for instance, may couple the head-end 200 tothe one or more controllers (e.g., to the controller 120 a). Thecommunication port 207 may be any suitable communication portimplementing any suitable communication protocol but, in an embodiment,is an Ethernet port implementing Ethernet communications. Additionalcommunication ports 204, 206, 209 a, and 209 b facilitate communicationbetween the head-end 200 and one or more distributed electronicmarshaling modules 210 (also referred to herein as “distributedmarshaling modules”) (see FIG. 4). The communication ports 204 and 206,for instance, may serve primarily as output and input ports,respectively, with the port 204 transmitting data from the head-end 200to the distributed marshaling modules 210, and the port 206 receivingdata at the head-end 200 from the distributed marshaling modules 210, asdescribed below. In embodiments, the ports 209 a and 209 b may havesimilar functionality and may service a second set of distributedmarshaling modules 210.

One such distributed marshaling module 210 is depicted in FIG. 4, inblock diagram format. The distributed marshaling module 210 is, in manyrespects, similar to the electronic marshaling module 148 depicted inFIG. 2G, in that it includes a circuitry block 216 that, in turn,includes a multiplicity of EMC slots 260 a-260 f, and a correspondingmultiplicity of terminal blocks 240 a-240 f. Each of the EMC slots 260a-260 f is configured to receive and be communicatively connected to acorresponding EMC 250 a-250 f. As described above, each of the EMCs 250a-250 f may (but need not necessarily) include a corresponding memorydevice 270 a-270 f, and/or each of the EMC slots 260 a-260 f maylikewise include (but need not necessarily do so) a corresponding memorydevice 280 a-280 f. As should by now be understood, each of the terminalblocks 240 a-240 f is configured to be communicatively coupled to acorresponding field device 220 a-220 f by a corresponding wire run (orwireless link) 230 a-230 f.

The EMCS 250 a-250 f function in the same was as described above withrespect to previous figures. That is, the each of the EMCs 250 a-250 fis selected according to the signals that will be transmitted on thecorresponding wire run 230 a-230 f between the distributed marshalingmodule 210 and the respective field device 220 a-220 f. Of course, whilethe distributed marshaling module 210 is depicted in FIG. 4 as havingsix EMC slots 260 a-260 f in the circuitry block 216, the number of EMCslots is but a single example embodiment, and a particular distributedmarshaling module 210 may include a circuitry block 216 having anyselected number of EMC slots including, for example, 2, 4, 6, 8, 10, 16,etc. Additionally, while the distributed marshaling module 210 isdepicted in FIG. 4 as having a single circuitry block 216, inembodiments the distributed marshaling module 210 is operable to supportmultiple circuitry blocks 216. In some embodiments, the circuitry block216 is modular, and multiple circuitry blocks 216, each disposed on acircuitry module card 217 or coupled together on a single circuitrymodule card 217, can be communicatively coupled to one another by aconnector (not shown), and may be supported/serviced by a singledistributed marshaling module 210.

In addition to the circuitry block 216, the distributed marshalingmodule 210 and, in particular, a communication module 218, may include apair of communication ports 212 and 214. In embodiments, thecommunication ports 212, 214 may be Ethernet communication portsconfigured to communicate via an Ethernet protocol. Generally, however,the communication ports 212, 214 may operate using any communicationprotocol and medium, known or developed in the future, suitable forproviding secure, timely, error-free network communication between thedistributed marshaling module 210 and I/O cards 203, 203′. Inembodiments, while both ports 212, 214 are operable to providebi-directional communication, each port may be primarily dedicatedparticularly to the transmit or receive functions.

Further, the distributed marshaling module 210 may include a scanningmodule 292 that is operable to scan the multiplicity of EMCs 250 a-250f. The scanning module 292 may be disposed on the circuitry module card217, with each circuitry block 216 having a dedicated scanning module292, or may be shared among a plurality connected circuitry blocks 216.In any event, the EMCs 250 a-250 may be scanned periodically (e.g.,using a multiplexer) to retrieve data or values from and/or transmitdata or values to each of the field devices 220 a-220 b. Data retrievedby the scanning module(s) 292 may be transmitted immediately to ahead-end 200 via the communication ports (described below) or may bestored temporarily in a memory device 290 until being transmitted to thehead-end 200, which may occur periodically, upon request, or somecombination of periodically and by request according to pre-programmedfunctionality. For instance, some values (e.g., a value received at theEMC 250 a from the field device 220 a) may be required to be transmittedperiodically (e.g, every second), while some values (e.g., a valuereceived at the EMC 250 b from the field device 220 b) may be requiredto be transmitted immediately upon a change in the value.

The operation of the scanning module 292 and the storage and/ortransmission of the values retrieved from the EMCs 250 a-250 f may becoordinated by a dedicated processor 293. The processor 293 maycooperate with a memory device 294 storing machine readable instructionsfor operating of the scanning module 292 and directing the transmissionto the head-end 200 of data received from the EMCs 250 a-250 f and/orthe transmission to the field devices 220 a-220 f of data received fromthe head-end 200. The processor 293 may also be responsible forgenerating, transmitting, and receiving various “heartbeat” signals(described below), and coordinating the transmission and receipt of datavia the pair of communication ports 212, 214 disposed on the distributedmarshaling module 210. In some embodiments, the microprocessor 293 maybe configured to perform the functions of the scanning module 292,thereby negating the need for a separate scanning module 292.Accordingly, in such embodiments, the scanning module 292 may beomitted.

While various memory devices 270 a-270 f, 280 a-280 f, 290, and 294 aredescribed, it should be understood that not all of these devices arerequired in a given embodiment. Rather, the various memory devices arerepresentative of the variety of locations in which memory devices maybe disposed, while accomplishing the goals and functions of the system(i.e., caching data where necessary, storing data, storingcomputer-readable instructions that cause the processor to control theoperation of the distributed marshaling module 210, etc.). Received ortransmitted data may be cached or stored in any (or a combination) ofthe memory devices 270 a-270 f, 280 a-280 f, 290, and 294. At the sametime, while the processor 293 is described as cooperating with thememory device 294, and the memory device 294 storing themachine-readable instructions executed by the processor 293, theprocessor 293 may, alternatively or additionally, cooperate with thememory device 290. Moreover, in embodiments, the processor device 293may be disposed on one or more of the circuitry module cards 217, ratherthan on the communication module 218 of the distributed marshalingmodule 210.

The head-end 200 may cooperate with one or more of the distributedmarshaling modules 210 to facilitate a distributed marshalingarchitecture 201, as depicted in FIG. 5. FIG. 5 depicts the head-end 200communicatively connected via the communication port 207 to thecontroller 120 a via the communication link 118 a, which may be anEthernet connection, for example. A communication link 213 a (which maybe an Ethernet connection) communicatively couples the communicationport 204 of the head-end 200 to a first communication port 212 a of afirst distributed marshaling module 210 a. The distributed marshalingmodule 210 a includes a circuitry block 216 a, to which six fielddevices 220 a-220 f are coupled via respective wire runs 230 a-230 f.Each of the wire runs 230 a-230 f terminates at a respective terminal,as described above, coupled to a respective EMC slot containing an EMCselected according to the signal format of the respective field device.The distributed marshaling module 210 a also includes a scanning module292 a, a memory device 290 a, and a processor 293 a.

A second communication port 214 a of the distributed marshaling module210 a is communicatively coupled via a connection 213 b (which may be anEthernet connection) to a first communication port 212 b of a seconddistributed marshaling module 210 b. The distributed marshaling module210 b, like the distributed marshaling module 210 a, includes acircuitry block 216 b, to which six field devices 222 a-222 f arecoupled via respective wire runs 232 a-232 f. Each of the wire runs 232a-232 f terminates at a respective terminal, as described above, coupledto a respective EMC slot containing an EMC selected according to thesignal format of the respective field device. The distributed marshalingmodule 210 b also includes a scanning module 292 b, a memory device 290b, and a processor 293 b.

FIG. 5 also depicts that a second communication port 214 b of thedistributed marshaling module 210 b is communicatively coupled via aconnection 213 c (which may be an Ethernet connection) to a firstcommunication port 212 c of a third distributed marshaling module 210 c.The distributed marshaling module 210 c, like the distributed marshalingmodules 210 a and 210 b, includes a circuitry block 216 c, to which sixfield devices 224 a-224 f are coupled via respective wire runs 234 a-234f. Each of the wire runs 234 a-234 f terminates at a respectiveterminal, as described above, coupled to a respective EMC slotcontaining an EMC selected according to the signal format of therespective field device. The distributed marshaling module 210 c alsoincludes a scanning module 292 c, a memory device 290 c, and a processor293 c. A connection 213 d communicatively connects a secondcommunication port 214 c on the distributed marshaling module 210 c tothe communication port 206 on the head-end 200.

The communication links/connections 213 a-213 d, in cooperation with thecommunication ports 204, 212 a-212 c, 214 a-214 c, and 206, form a“ring” architecture, in which data are passed from one device to thenext until reaching the intended destination device. In a ringarchitecture, each communication device (e.g., the distributedmarshaling modules 210 a-210 c, the head-end 200) is communicativelycoupled to only two other devices, and each places data onto thecommunication ring associated with a specified destination device (whichmay be specified with a destination address or ID), such that the datamoves around the communication ring, from device to device, until itreaches its destination. That is, each successive device on thecommunication ring receives the data, determines whether thecorresponding destination corresponds with that device and, if not,forwards the data on to the next successive device on the communicationring. Because each device typically has two ports, one functioning as a“receive” port and one functioning as a “transmit” port, each device istypically connected to only two other devices on the ring.

The flow of data will be described, by way of example, with reference tothe distributed marshaling module 210 b. The scanning module 292 b ofthe distributed marshaling module 210 b may continually, andperiodically (e.g., once per second, ten times per second, etc.), scaneach of the EMCs associated with the field devices 222 a-222 f connectedto the circuitry block 216 b. At any given moment, the signaltransmitted by a given one of the field devices 222 a-222 f (e.g., thefield device 222 a) is being transmitted from the field device to theassociated EMC via the respective wire run (e.g., the wire run 232 a).For some signals, the signal is always present on the wire run and maybe periodically sampled by the EMC. For other signals, the signal may betransmitted by the field device periodically or upon request, andreceived at the EMC. Either way, the EMC coupled to each field devicemay, at any given time, have registered a present or most recent valuereceived from the field device. The scanning module 292 b periodicallyqueries each of the EMCs on the distributed marshaling module 210 b andthen may cache or store the values for each of the EMCs (and each of thefield devices) in, for example, the memory device 290 b.

The processor 293 b may periodically, on a schedule, or upon request bythe head-end 200, transmit the values stored in the memory device 290 bto the head-end 200. In so doing, the processor 293 b may retrieve fromthe memory device 290 b the data to be transmitted, associate adestination device (e.g., the head-end 200) with the data, and transmitthe data from the port 214 b to the port 212 c of the distributedmarshaling module 210 c via the communication link 213 c. The processor293 c on the distributed marshaling module 210 c may receive the datavia the port 212 c, determine that the data are not addressed to thedistributed marshaling module 210 c (because the data are associatedwith a destination address indicating the head-end 200) and proceed totransmit the data from the port 214 c on the communication link 213 d.The data are received at the port 206 by the head-end 200, and theprocessor 205 may determine that the received data are associated withthe address for the head-end 200 and may process the data.

Processing the received data at the head-end 200 may include storing orcaching the data for later transmission to the controller 120 a via oneof the I/O cards 202, 202′, or transmitting the data immediately to thecontroller 120 via one of the I/O cards 202, 202′. Specifically, thehead-end 200 may receive all data for all of the EMCs connected to thehead-end 200 via the connected distributed marshaling modules 210 a-210c, and may store the data in a local database, e.g., in the memorydevice 208. The head-end 200 may then answer requests, received from aconnected controller (e.g., from the controller 120 a) for data fromspecific EMCs, as if each EMC were local to the head-end 200 (e.g., asif the EMCs and I/O cards were configured as in FIG. 2G).

A similar process may be engaged to send data from the controller 120 ato a particular field device. For instance, if the controller 120 aneeds to send data to the field device 222 c, the controller 120 a maysend the data via the I/O card(s) 202, 202′ to the head-end 200. The I/Ocards 202, 202′ may be generally programmed such that each field deviceis associated with a particular one of the EMCs and may include in thedata package the EMC for which the data are destined. The head-end 200may determine which of the distributed marshaling modules 210 a, 210 b,210 c is associated with the destination EMC 222 c and, upon making thedetermination, may associate the data with the address of thedistributed marshaling module 210 b. Thus, if the data are destined forthe field device 222 c, the data will be associated with the destinationaddress for the distributed marshaling module 210 b, before beingtransmitted from the head-end 200 via the port 204, and being receivedvia the connection 213 a at the port 212 a of the distributed marshalingmodule 210 a. Upon receipt at the port 212 a, the processor 293 a maydetermine that the destination address of the data received on the port212 a is not the same as the destination address of the distributedmarshaling module 210 a, and may transmit the data on the port 214 a.Thereafter, upon receiving the data at the port 212 b via the connection213 b, the processor 293 b may determine that the destination address ofthe data received on the port 212 b is the same as the destinationaddress of the distributed marshaling module 210 b, indicating that thedata are destined for an EMC on the distributed marshaling module 210 b.The processor 293 b may determine from the received data, which EMC thedata are destined for, and may place the data on the EMC, where it istransmitted to the field device 222 c via the wiring run 232 c.

The destination address associated with the data placed on thecommunication ring may, in various embodiments, be an address associatedwith the distributed marshaling module or head-end hardware itself, anaddress of the EMC for which the data are destined, an I/O channeladdress, or an address (e.g., device tag or device signal tag) of thefield device or controller device for which the data are destined. As anexample, data placed on the communication ring may be associated with anaddress of a particular device, such as a field device or acontroller—the ultimate device for which the data are destined. In suchan embodiment, each distributed marshaling module 210 would keep in itsmemory device 294 a listing, database, or other such data structurestoring the device addresses of the devices coupled to it, such that theprocessor 293 may compare the address associated with specific data withthe addresses to which it has immediate access. If, upon receiving data,the processor 293 finds that the destination address associated with thedata matches the address (e.g., the field device tag or data signal tag)of a device attached to the distributed marshaling module 210, then theprocessor 293 may route the data to that device via the associated EMC.On the other hand, if the processor 293 finds that the destinationaddress associated with the data does not match any of the addresses inthe data structure of the memory device 294, the processor 293 maytransmit that data to the next device on the communication ring.

As another example, data placed on the communication ring may beassociated with an address associated with a specific EMC (i.e., theaddress of the EMC itself, rather than of the field device coupled tothe EMC). In such an embodiment, each distributed marshaling module 210would keep in its memory device 294 a listing, database, or other suchdata structure storing the addresses of each of the EMCs populating theEMC slots of the distributed marshaling module, such that the processor293 may compare the address associated with specific data with theaddresses of the local EMCs. If, upon receiving data, the processor 293finds that the destination address associated with the data matches theaddress of a local EMC, then the processor 293 may route the data to theEMC, which may communicate the data to the field device coupled to theEMC. On the other hand, if the processor 293 finds that the destinationaddress associated with the data does not match any of the EMC addressesin the data structure of the memory device 294, the processor 293 maytransmit that data to the next device on the communication ring.

With regard to data being sent to field devices (e.g., the field device220 a) by a controller (e.g., the controller 120 a), the destinationaddress may therefore be associated with the data directly by thecontroller 120 a in embodiments in which the destination address is thedevice tag or device signal tag associated with the field device.However, in embodiments in which the destination address is an addressassociated with the EMC to which the field device is coupled, thedestination address may associated with the data by, for example, thehead-end 200 itself. For instance, the head-end 200 may receive from thecontroller 120 a data destined for a particular field device (e.g., thefield device 220 a) associated with a device tag for that field device.The head-end 200 may receive the data via the I/O card 202, and maydetermine that the field device in question (220 a) is associated with aparticular I/O channel of the I/O card 202. The head-end 200 may thenassociate the data with a destination address for the EMC (e.g., a tagassociated with the EMC itself), or a destination address for a specificdistributed marshaling module and channel of the distributed marshalingmodule corresponding to the EMC (e.g., “module210 a-slot0”). Eachdistributed marshaling module then, upon receiving the data, wouldexamine (in the processor 293) the destination address to determinewhether the destination address was associated with the distributedmarshaling module.

As described above, data are typically received on one communicationport of each of the devices on the communication ring, and transmittedon another communication port of each of the devices on thecommunication ring, resulting in data flowing generally in one directionon the ring. However, the communication ring and architecture describedherein are flexible enough that the data may flow in either direction,providing additional reliability and redundancy. Among its otherfunctions, each of the processors 293 a-293 c and 205 is programmed (byinstructions stored on the memory devices 290 a-290 c, 208, etc., forexample) to generate, transmit, receive, and interpret “heartbeat”signals. The heartbeat signals are periodic (e.g., every 5 ms) signalsof a known format or series of bits, that indicate to each device thatthe next device in the ring (e.g., the device connected to thecommunication port) is present and operational. That is, each devicesends out a periodic heartbeat signal on each of its two ports (on thecommunication ring), and the adjacent devices receive the heartbeatsignal and know that the device from which the signal is received ispresent and operational. By way of example, the processor 205 sends aheartbeat signal on the port 204 and, upon receiving the heartbeatsignal at its port 212 a, the processor 293 a on the distributedmarshaling module 210 a can determine that the communication link 213 ais operable and coupled to an operable device. The processor 205 alsosends a heartbeat signal on the port 206 and, upon receiving theheartbeat signal at its port 214 c, the processor 293 c on thedistributed marshaling module 210 c can determine that the communicationlink 213 d is operable and coupled to an operable device. The samebehavior holds true for each of the distributed marshaling modules 210a-210 c, each processor sends heartbeats to the adjacent devices via theports 212, 214 and receives from adjacent devices the heartbeats sent bythe respective processors of those distributed marshaling modules.

In the event that one of the processors 293 a-293 c, 205 does notreceive a heartbeat signal on one of the two associated communicationports (212 a-212 c and 214 a-214 c, or 204 and 206, respectively), theprocessor in question ceases to transmit data on that port, and bothtransmits and receives on the other port. Thus, if the processor 293 cdoes not receive a heartbeat signal on the communication port 214 c, theprocessor 293 c would transmit data on the port 212 c, instead of on theport 214 c.

Additionally, each of the processors 293 a-293 c, 205 may be programmedto reverse the flow of data in the event that it receives data on acommunication port typically used for transmitting (i.e., if data arebeing transmitted the “wrong” direction on the communication ring).Thus, continuing the example above, if the processor 293 c transmitteddata on the port 212 c, the processor 293 b of the distributedmarshaling module 210 b would be programmed, upon receiving data on theport 214 b (which generally transmits data) to transmit its data(including data received on the port 214 b for which the distributedmarshaling module 210 b is not the destination) on the port 212 b.

In another embodiment, depicted in FIG. 6, the head-end 200 supports twosets of distributed marshaling modules: a first set of distributedmarshaling modules 210 a and 210 b; and a second set of distributedmarshaling modules 210 c and 210 d. Each set of distributed marshalingmodules functions generally as described with respect to FIG. 5,however, in FIG. 6, while the distributed marshaling module 210 a andthe distributed marshaling module 210 b are coupled to the head-end 200by the ports 204 and 206 of the head-end 200, the distributed marshalingmodule 210 c and the distributed marshaling module 210 d are coupled tothe head-end 200 by a set of similar ports 209 a and 209 b. The port 209a functions in much the same way as the port 204, while the port 209 bfunctions in much the same way as the port 206. In this manner,additional flexibility is afforded to the plant engineers designing andconfiguring the process plant 5, by allowing one distributed EMC ring toservice one physical area of the process plant 5, while anotherdistributed EMC ring services another physical area of the process plant5, yet both distributed EMC rings can be serviced by the head-end 200,the same I/O cards 202, 202′, and the same controller 120 a.

In the embodiments described with respect to FIGS. 5 and 6, the EMCs ineach of the distributed marshaling modules 210 a-210 d appear to thecontroller 120 a as if each was in the same marshaling cabinet (e.g.,the cabinet 115 a) adjacent to the I/O card carrier 142. As a result,the embodiments described with respect to FIGS. 3-6, can be implementedin process control systems that already implement an architectureimplementing EMCs (e.g., that of FIG. 2A-2G) without requiring anychanges to the software of the controller 120 a.

Another benefit of the embodiments illustrated in FIGS. 5 and 6 is thatEMCs can be moved from a marshaling cabinet (e.g., the cabinet 115 a)that is remote from the field devices with which the EMCs areassociated, to a distributed marshaling module that is proximate to thefield devices, simply by re-landing the wiring run from the field deviceat the distributed marshaling module and moving the EMC from themarshaling cabinet to the distributed marshaling module. As far as theoperation of the controller is concerned, there is no difference.

While the distributed marshaling system has, until this point, beendescribed as communicating via a ring architecture, it should beunderstood that the distributed marshaling system, and the componentstherein, are amenable to other embodiments and configurations as welland, specifically, to other communication architectures. For instance,FIG. 7 depicts an architecture 300 in which a head-end 200 iscommunicatively connected to each of one or more distributed marshalingmodules. While depicted in FIG. 7 as three distributed marshalingmodules 310 a, 310 b, and 310 c, the architecture 300 could have anynumber of distributed marshaling modules, as long as the total number ofEMCs populated on those distributed marshaling modules is less than orequal to the number of channels supported by the I/O cards (not shown inFIG. 7) on the head-end 200. Each of the distributed marshaling modules310 a, 310 b, and 310 c depicted in FIG. 7 includes a respectivecircuitry block 216 a, 216 b, and 216 c configured to receive andcommunicate with a set of EMCs (not shown in FIG. 7) that can be coupledby respective wiring runs 230, 232, 234 to sets 220, 222, 224 of fielddevices.

In contrast to the architecture depicted in FIG. 5, the architecture 300is not a ring architecture, but generally operates the same way as thering architecture would operate if the port 204 (in FIG. 5) were notoperational. That is, signals are communicated along the communicationpath, with each distributed marshaling module acting as a bridge for theothers. By way of example, data destined for the head-end 200 from thedistributed marshaling module 310 c would be transmitted to thedistributed marshaling module 310 b via a communication link 313 cbetween the port 212 c and the port 214 b. The distributed marshalingmodule 310 b (specifically, the processor thereon) would forward thedata over a link 313 b between the ports 212 b and 214 a to thedistributed marshaling module 310 a. The distributed marshaling module310 a (specifically, the processor thereon) would forward the data overa link 313 a between the ports 212 a and 206 to the head-end 200. Dataflowing the other direction—from the head-end 200 to one of thedistributed marshaling modules 310 a, 310 b, 310 c, for example—wouldmove similarly between the various distributed marshaling modules untilreaching the destination device.

FIG. 8 depicts another architecture 350 in which a head-end 200 iscommunicatively connected to each of one or more distributed marshalingmodules in a star communication configuration. (It will be understoodthat if when the head-end is connected to only a single distributedmarshaling module, the architectures 300 and 350 are essentially thesame.) While depicted in FIG. 8 as five distributed marshaling modules310 a, 310 b, 310 c, 310 d, and 310 e, the architecture 350 could haveany number of distributed marshaling modules, as long as the totalnumber of EMCs populated on those distributed marshaling modules is lessthan or equal to the number of channels supported by the I/O cards (notshown in FIG. 8) on the head-end 200. Each of the distributed marshalingmodules 310 a, 310 b, 310 c, 310 d, and 310 e depicted in FIG. 8includes a respective circuitry block 216 a, 216 b, 216 c, 216 d, and216 e configured to receive and communicate with a set of EMCs (notshown in FIG. 8) that can be coupled by respective wiring runs 230, 232,234, 236, and 238 to sets 220, 222, 224, 226, and 228 of field devices.

Like the architecture 300 of FIG. 7, the architecture 350 is not, perse, a ring architecture. In the architecture 350, each of thedistributed marshaling modules 310 a, 310 b, 310 c, and 310 d is coupleddirectly to the head-end 200, via respective ports 206, 204, 209 a, and209 b of the head-end 200 coupled to respective ports 212 a, 212 b, 214c, and 212 d. While depicted as having only four communication ports forcommunicating with distributed marshaling modules, it should beunderstood that the head-end 200 may have fewer or more ports thandepicted, and may support as many distributed marshaling modules asdesired, so long as the number of EMCs populated on the distributedmarshaling modules is less than or the same as the number of channelssupported by the I/O cards.

Additionally, the various configurations may, in some embodiments, becombined. That is, the architecture depicted in FIG. 7, for example, maybe combined with the star architecture generally depicted in FIG. 8.FIG. 8 provides an example of such a combination of architectures. InFIG. 8, the distributed marshaling module 310 d is communicativelyconnected to the head-end 200 by a connection 352 d between the port 212d of the distributed marshaling module 310 d and the port 209 b of thehead-end 200. However, as illustrated in FIG. 7, the distributedmarshaling modules may communicate with other in-line distributedmarshaling modules. In this case, a further distributed marshalingmodule 310 e is coupled to the distributed marshaling module 310 d by aconnection 352 e between a port 212 e of the distributed marshalingmodule 310 e and the port 214 d of the distributed marshaling module 310d. While the distributed marshaling module 310 d communicates directlywith the head-end 200 (as does each of distributed marshaling modules310 a, 310 b, and 310 c), in the architecture 350 the distributedmarshaling module 310 d also communicates data between the distributedmarshaling module 310 e and the head-end 200.

FIG. 9 illustrates yet another example architecture 400. In the examplearchitecture 400, the star communication architecture (illustrated inFIG. 8 between distributed marshaling modules 310 a, 310 b, and 310 cand head-end 200) is combined with a ring communication architecturesimilar to that depicted in FIG. 5. Specifically, the distributedmarshaling modules 310 a, 310 d, and 310 e form a communication ring 425with the head-end 200, with each node (i.e., each of the distributedmarshaling modules and the head-end) coupled to exactly two other nodes.The head-end 200 communicates with the distributed marshaling modules310 a, 310 d, and 310 e on the communication ring 425 via the ports 206and 209 b, in this embodiment. (It should be understood that theselection of ports of the head-end 200 as communicating with particulardevices in particular configurations is selectable and, accordingly,there is no requirement that specific pairs of ports cooperate orcommunicate with specific communication architectures.) A connection 402d between the port 209 b and the port 212 d couples the head-end 200 tothe distributed marshaling module 310 d; a connection 402 e between theports 214 d and 212 e couples the distributed marshaling modules 310 dand 310 e; a connection 402 f between the ports 214 e and 214 a couplesthe distributed marshaling modules 310 e and 310 a; and a connection 402e between the ports 206 and 212 a couples the distributed module 310 ato the head-end 200. The distributed modules 310 a, 31 d, and 310 e, andthe head-end 200, in FIG. 9 communicate in a manner similar to themanner in which the head-end 200 communicates with the distributedmarshaling modules 210 a, 210 b, and 21 c in FIG. 5.

In the architectures of FIGS. 7-9—architectures that implementcommunication paradigms other than the ring architecture—the addressingscheme may differ from that described above with respect to the ringarchitectures. Because such architectures have only a single path fromany distributed marshaling module to the head-end, each of thedistributed marshaling modules may be programmed to know which of thepair of communication ports on the distributed marshaling module has apath to the head-end. With reference again to FIG. 7, for example, thedistributed marshaling modules 310 a, 310 b, and 310 c may each beprogrammed to know, for a specific set of distributed marshaling modulesand head-end, that data destined for the head-end 200 must betransmitted on ports 212 a, 212 b, and 212 c, respectively.Alternatively, in embodiments, the distributed marshaling modules areconfigured such that, when the process plant is commissioned, it isimperative that the head-end always be available on one of the ports ofeach distributed marshaling module and not the other (i.e., that apre-condition of the architecture is that the head-end be available onthe ports 212, and not on the ports 214, or vice versa). In eitherevent, each of the distributed marshaling modules 310 a, 310 b, and 310c is programmed (specifically, the associated processor is programmed)that data received on a first of the two ports, if not addressed to thedistributed marshaling module or to a device (i.e., an EMC or fielddevice) coupled to the distributed marshaling module, is retransmittedon a second of the two ports. In this manner, each distributedmarshaling module forwards data down the chain of distributed marshalingmodules if the address associated with the data does not correspond tothat distributed marshaling module.

The head-end 200, meanwhile, may maintain a database (e.g., in thememory device 208) of address information that permits the head-end 200to know which field devices, EMCs, and/or distributed marshaling modulesare coupled to each of the communication ports of the head-end 200 thatis connected to the controller. With reference to FIG. 8, such adatabase will provide the head-end 200 and, in particular, the processordisposed on the head-end 200, with the necessary information to selectone of the ports 204, 206, 209 a, or 209 b from which to transmit datadestined for a given field device, EMC, and/or distributed marshalingmodule.

In any of the embodiments described explicitly herein, or that will beapparent to those of ordinary skill in the art in view of thisspecification, it is contemplated that the communication connectionsbetween the distributed marshaling modules and the head-end may alsosupply power to the distributed marshaling modules, to the EMCspopulated in the circuitry blocks of the distributed marshaling modules,and even to the field devices connected to the EMCs. Any known method ofproviding power over a network connection may be implemented, includingPower over Ethernet (PoE).

Though a variety of methods will be apparent from the description above,FIG. 10 is a flow diagram depicting one particular method 500 ofcommunicating data from a field device in a process plant to acontroller in the process plant. A field device is communicativelycoupled, via a wiring run, to a terminal block that is, in turn,communicatively coupled to a distributed marshaling module and,specifically, to an EMC slot populated with an EMC. The EMC may be an AIEMC configured to receive from the field device an analog signal, an AOEMC configured to provide to the field device an analog signal, a DI EMCconfigured to receive from the field device a discrete input, a DO EMCconfigured to provide to the field device a discrete signal, or anyother type of EMC for interfacing an I/O card to a field device. In anyevent, a signal representative of the data being communicated isreceived from the field device at the terminal block (block 502). TheEMC converts the signal received from the field device to a secondsignal that is compatible with an I/O card (block 504). The EMC isscanned to register the second signal (block 506). The microprocessor onthe distributed marshaling module transmits a signal indicative of theregistered second signal to a head-end module remote from themicroprocessor and the EMC (block 508), which in embodiments iscommunicatively coupled to the controller via an I/O card, via either afirst communication port or a second communication port (block 510). Inembodiments, the microprocessor transmits the signal indicative of theregistered second signal via the first communication port by default,but transmits the signal indicative of the registered second signal viathe second communication port if no periodic heartbeat signal isdetected on the first communication port within a predetermined periodbefore transmitting. In embodiments, transmitting the signal indicativeof the registered second signal includes transmitting the signalindicative of the registered second signal to an intervening distributedmarshaling module disposed in the communication path to the head-endmodule, which communication path may comprise a ring architecture.

Other Considerations

It is noted that while the apparatus, systems, and methods describedherein are described with respect to a process control system 5, any oneor more of the apparatus, systems, and methods described herein areequally applicable to a process control safety information system of aprocess control plant, such as the DeltaV SIS™ product provided byEmerson Process Management. For example, a standalone process controlsafety system or an integrated control and safety system (“ICSS”) may beconfigured using any one or more of the apparatus, systems, and methodsdescribed herein.

Additionally, when implemented in software (e.g., computer-readableinstructions), any of the applications, services, and engines describedherein may be stored in any tangible, non-transitory computer readablememory such as on a magnetic disk, a laser disk, solid state memorydevice, molecular memory storage device, or other storage medium, in aRAM or ROM of a computer or processor, etc. Although the example systemsdisclosed herein are disclosed as including, among other components,software and/or firmware executed on hardware, it should be noted thatsuch systems are merely illustrative and should not be considered aslimiting. For example, it is contemplated that any or all of thesehardware, software, and firmware components could be embodiedexclusively in hardware, exclusively in software, or in any combinationof hardware and software. Accordingly, while the example systemsdescribed herein are described as being implemented in software executedon a processor of one or more computer devices, persons of ordinaryskill in the art will readily appreciate that the examples provided arenot the only way to implement such systems.

Thus, while the present invention has been described with reference tospecific examples, which are intended to be illustrative only and not tobe limiting of the invention, it will be apparent to those of ordinaryskill in the art that changes, additions or deletions may be made to thedisclosed embodiments without departing from the spirit and scope of theinvention. Further, although the forgoing text sets forth a detaileddescription of numerous different embodiments, it should be understoodthat the scope of the patent is defined by the words of the claims setforth at the end of this patent and their equivalents. The detaileddescription is to be construed as exemplary only and does not describeevery possible embodiment because describing every possible embodimentwould be impractical, if not impossible. Numerous alternativeembodiments could be implemented, using either current technology ortechnology developed after the filing date of this patent, which wouldstill fall within the scope of the claims and all equivalents thereof.

The particular features, structures, or characteristics of any specificembodiment may be combined in any suitable manner and in any suitablecombination with one or more other embodiments, including the use ofselected features without corresponding use of other features. It is tobe understood that other variations and modifications of the embodimentsof the present disclosure described and illustrated herein are possiblein light of the teachings herein and are to be considered part of thespirit and scope of the present disclosure. By way of example, and notlimitation, the present disclosure contemplates at least the followingaspects:

1. A process control system operating to control a process in a processplant, comprising: a plurality of process control field devices; aninput/output (I/O) card communicatively coupled to the plurality ofprocess control field devices; a controller, communicatively coupled tothe I/O card and receiving, via the I/O card, data from the plurality ofprocess control field devices, and operating to send, also via the I/Ocard, control signals to one or more of the process control fielddevices to control the operation of the process; a distributedmarshaling module comprising: a pair of communication ports; one or moreelectronic marshaling component slots, at least one electronicmarshaling component slot having disposed therein an electronicmarshaling component; and a respective terminal block corresponding toeach of the one or more electronic marshaling component slots, theterminal block for the at least one electronic marshaling component slotbeing communicatively coupled to one of the plurality of field devices;a microprocessor, coupled to the pair of communication ports; and ahead-end module comprising: a first communication port coupling thehead-end module to the I/O card; a pair of second communication portscommunicatively coupled to the distributed marshaling module; a memorydevice having stored thereon a database storing information received bythe microprocessor via the pair of second communication ports; and amicroprocessor, coupled to the memory device, configured to: receive andtransmit data via the pair of second communication ports; store receiveddata to the memory device; retrieve data from the memory device; andtransmit retrieved data to the controller via the I/O card.

2. A process control system according to aspect 1, wherein the pair ofcommunication ports on the distributed marshaling module cooperate withthe pair of second communication ports on the head-end module to form aring architecture.

3. A process control system according to either aspect 1 or aspect 2,wherein the microprocessor on the head-end module sends a periodicheartbeat signal on each of the pair of second communication ports andthe microprocessor on the distributed marshaling module sends a periodicheartbeat signal on each of the pair of communication ports.

4. A process control system according to any one of the precedingaspects, wherein the process control system comprises a plurality ofdistributed marshaling modules.

5. A process control system according to any one of the precedingaspects, wherein the electronic marshaling component is configured toreceive a signal from the one of the plurality of field devices and toconvert the received signal from a first form to a second form.

6. A process control system according to any one of the precedingaspects, wherein the distributed marshaling module further comprises: ascanning module operable to scan each of the electronic marshalingcomponent slots and, for any slot in which there is an electronicmarshaling component, to register a value associated with the slot.

7. A process control system according to aspect 6, wherein themicroprocessor on the distributed marshaling module functions as thescanning module.

8. A process control system according to either aspect 6 or aspect 7,wherein the microprocessor on the distributed marshaling moduletransmits the value associated with the slot on one of the pair ofcommunication ports.

9. A process control system according to any one of the precedingaspects, wherein the microprocessor on the distributed marshalingmodule, by default, transmits data through a first one of the pair ofcommunication ports, and receives data through a second one of the pairof communication ports.

10. A process control system according to any one of the precedingaspects, wherein the microprocessor on the distributed marshaling moduletransmits information on a given one of the pair of communication portsonly if the microprocessor on the distributed marshaling module hasdetected a heartbeat signal on the given one of the pair ofcommunication ports within a pre-defined time period prior totransmitting.

11. A process control system according to any one of the precedingaspects, wherein the microprocessor on the head-end module, by default,transmits data through a first one of the pair of second communicationports, and receives data through a second one of the pair of secondcommunication ports.

12. A process control system according to any one of the precedingaspects, wherein the microprocessor on the head-end module transmitsinformation on a given one of the pair of second communication portsonly if the microprocessor on the head-end module has detected aheartbeat signal on the given one of the pair of second communicationports within a pre-defined time period prior to transmitting.

13. A process control system according to any one of the precedingaspects, wherein the I/O card is disposed on the head-end module.

14. A process control system according to any one of the precedingaspects, wherein the electronic marshaling component is one of an AOelectronic marshaling component, an AI electronic marshaling component,a DO electronic marshaling component, or a DI electronic marshalingcomponent.

15. A process control system according to any one of the precedingaspects, wherein the microprocessor on the head-end module is furtherconfigured to: receive data from the controller via the I/O card;associate the data received from the controller with a destinationaddress specifying one of a destination distributed marshaling moduleassociated with a specific one of the field devices, a destinationelectronic marshaling component associated with the specific one of thefield devices, or the specific one of the field devices; and transmitthe data received from the controller, and the associated destinationaddress, to the specific one of the field devices by the transmittingthe data on one of the pair of second communication ports.

16. A process control system according to aspect 15, wherein a first oneof the pair of communication ports on the distributed marshaling moduleis communicatively coupled to the one of the pair of secondcommunication ports on which the microprocessor on the head-end moduletransmitted the data, and further wherein: the microprocessor on thedistributed marshaling module receives the data transmitted from thehead-end module, determines whether the destination address isassociated with the distributed marshaling module, and: if thedestination address is associated with the distributed marshalingmodule, routes the data to the specific one of the field devices, if thedestination address is not associated with the distributed marshalingmodule, transmits the data and the associated destination address on thesecond one of the pair of communication ports on the distributedmarshaling module.

17. A process control system according to any one of the precedingaspects, wherein the microprocessor on the distributed marshaling moduleis configured to: receive data, including a destination address, on afirst one of the pair of communication ports and, if the destinationaddress specifies the head-end module, transmit the data, including thedestination address, on the second one of the pair of communicationports.

18. A process control system according to any one of the precedingaspects, wherein each of the pair of second communication ports iscoupled to one of the pair of communication ports on the distributedmarshaling module by an Ethernet connection.

19. A process control system according to any one of the precedingaspects, wherein an Ethernet connection communicatively connects thehead-end module to the distributed marshaling module.

20. A process control system operating to control a process in a processplant, comprising: a plurality of process control field devices; aninput/output (I/O) card communicatively coupled to the plurality ofprocess control field devices; a controller, communicatively coupled tothe I/O card and receiving, via the I/O card, data from the plurality ofprocess control field devices, and operating to send, also via the I/Ocard, control signals to one or more of the process control fielddevices to control the operation of the process; a plurality ofdistributed marshaling modules, each distributed marshaling modulecomprising: a pair of communication ports; a plurality of electronicmarshaling component slots; an electronic marshaling component disposedin an electronic marshaling component slot; and a respective terminalblock corresponding to each of the plurality of electronic marshalingcomponent slots, the terminal block for the electronic marshalingcomponent slot in which the electronic marshaling component is disposedbeing communicatively coupled to one of the plurality of field devices;and a microprocessor, coupled to the pair of communication ports; and ahead-end module comprising: a first communication port coupling thehead-end module to the I/O card; a second communication portcommunicatively coupled to a first one of the plurality of distributedmarshaling modules; a third communication port communicatively coupledto a second one of the plurality of distributed marshaling modules; amemory device having stored thereon a database storing informationreceived by the microprocessor via the second and third communicationports; and a microprocessor, coupled to the memory device, configuredto: receive and transmit data via the second and third communicationports; store received data to the memory device; retrieve data from thememory device; and transmit retrieved data to the controller via the I/Ocard.

21. A distributed marshaling module for coupling field devices in aprocess plant to a controller in the process plant, comprising: a pairof communication ports; a first number of electronic marshalingcomponent slots; a second number, equal to the first number, of terminalblocks, each terminal block in communicative connection with one of theelectronic marshaling component slots and configured to becommunicatively connected to a respective one of the field devices; athird number, less than or equal to the first number, of electronicmarshaling components disposed in the electronic marshaling componentslots, each of the electronic marshaling components configured toreceive a signal from the respective one of the field devices and toconvert the received signal to a format compatible with an I/O card; anda microprocessor coupled to the pair of communication ports.

22. A distributed marshaling module according to aspect 21, wherein themicroprocessor is configured to transmit and receive data on the pair ofcommunication ports.

23. A distributed marshaling module according to either aspect 21 oraspect 22, wherein the microprocessor is configured to transmit on afirst one of the pair of communication ports by default, and to receiveon a second one of the pair of communication ports by default.

24. A distributed marshaling module according to aspect 23, wherein themicroprocessor is further configured to transmit on the second one ofthe pair of communication ports instead of the first one of the pair ofcommunication ports if the microprocessor has not received an expectedperiodic heartbeat signal on the first one of the pair of communicationports within a predetermined period of time prior to transmitting.

25. A distributed marshaling module according to any one of aspects 21to 24, wherein the microprocessor is configured to transmit a periodicheartbeat signal on each of the pair of communication ports.

26. A distributed marshaling module according to any one of aspects 21to 25, further comprising a scanning module operable to: scan theelectronic marshaling component slots; receive the converted signalsfrom each of the electronic marshaling components; and eithercommunicate the received converted signals to the microprocessor fortransmission to a head-end module, or store the received convertedsignals in a memory device for later retrieval and transmission to thehead-end by the microprocessor.

27. A distributed marshaling module according to aspect 26, wherein themicroprocessor is configured as the scanning module.

28. A distributed marshaling module according to any one of aspects 21to 27, wherein the microprocessor is configured to: receive data via oneof the pair of communication ports, the received data including adestination address; determine whether the destination address isassociated with the distributed marshaling module; and either transmitthe received data via one of the pair of communication ports if thedestination address is not associated with the distributed marshalingmodule, or route the received data to a field device communicativelycoupled to a terminal block on the distributed marshaling module, byrouting the received data to the electronic marshaling componentcorresponding to the field device.

29. A distributed marshaling module according to aspect 28, wherein thedestination address specifies one of: (1) a head-end; (2) a field devicecoupled to the distributed marshaling module; or (3) a field devicecoupled to another distributed marshaling module.

30. A distributed marshaling module according to aspect 28, wherein thedestination address specifies one of: (1) a head-end; (2) an electronicmarshaling component associated with the distributed marshaling module;or (3) an electronic marshaling component associated with anotherdistributed marshaling module.

31. A distributed marshaling module according to aspect 28, wherein thedestination address specifies one of: (1) a head-end; (2) thedistributed marshaling module; or (3) another distributed marshalingmodule.

32. A head-end module for coupling field devices in a process plant to acontroller in the process plant, comprising: a first communication portcommunicatively connecting the head-end module to a first distributedmarshaling module, the first distributed marshaling module part of afirst ring architecture; a second communication port communicativelyconnecting the head-end module to a second distributed marshalingmodule, the second distributed marshaling module part of the first ringarchitecture; a third communication port communicatively connecting thehead-end module to an I/O card, the I/O card communicatively connected,in turn, to the controller; a memory device; a microprocessor, coupledto the memory device, and configured to: receive, via one or both of thefirst and second communication ports, first data from field devicescoupled to the first and second distributed marshaling modules; storethe received first data to a database disposed in the memory device;retrieve the received first data from the database; transmit theretrieved first data to the controller via the I/O card; receive seconddata from the controller via the I/O card; and transmit, via one or bothof the first and second communication ports, the second data tospecified ones of the field devices.

33. A head-end module according to aspect 32, wherein the microprocessoris configured to transmit on a first one of the first and secondcommunication ports by default, and to receive on a second one of thefirst and second communication ports by default.

34. A head-end module according to aspect 33, wherein the microprocessoris further configured to transmit on the second communication portinstead of the first communication port if the microprocessor has notreceived an expected periodic heartbeat signal on the firstcommunication port within a predetermined period of time prior totransmitting.

35. A head-end module according to any one of aspects 32 to 34, whereinthe microprocessor is configured to transmit a periodic heartbeat signalon each of the first and second communication ports.

36. A head-end module according to any one of aspects 32 to 35, whereinthe microprocessor is configured to: receive data via one of the firstor second communication ports, the received data including a destinationaddress; determine whether the destination address is an address of thehead-end module; and either transmit the received data via one of thefirst or second communication ports if the destination address is notthe address of the head-end module or, if the destination address is theaddress of the head-end module, store the received data in the database.

37. A head-end module according to aspect 36, wherein the destinationaddress specifies one of: (1) the head-end; or (2) a field devicecoupled to one of the distributed marshaling modules.

38. A head-end module according to aspect 36, wherein the destinationaddress specifies one of: (1) the head-end; or (2) an electronicmarshaling component associated with one of the distributed marshalingmodules.

39. A head-end module according to aspect 36, wherein the destinationaddress specifies one of: (1) the head-end; or (2) one of thedistributed marshaling modules.

40. A head-end module according to any one of aspects 32 to 39, furthercomprising: a fourth communication port communicatively connecting thehead-end module to a third distributed marshaling module, the thirddistributed marshaling module part of a second ring architecture; and afifth communication port communicatively connecting the head-end moduleto a fourth distributed marshaling module, the fourth distributedmarshaling module part of the second ring architecture.

41. A method of communicating data from a field device in a processplant to a controller in the process plant, the method comprising:receiving from the field device, at a terminal block, a signalrepresentative of the data; converting, in an electronic marshalingcomponent communicatively connected to the terminal block, the receivedsignal to a second signal; registering the second signal from theelectronic marshaling component; and transmitting, from amicroprocessor, to a head-end module remote from the microprocessor andthe electronic marshaling component, via either a first communicationport or a second communication port, a signal indicative of theregistered second signal.

42. The method according to aspect 41, wherein the signal indicative ofthe registered second signal is transmitted to the head-end module viathe first communication port, by default, and via the secondcommunication port if no periodic heartbeat signal is detected on thefirst communication port within a predetermined period beforetransmitting.

43. The method according to either aspect 41 or aspect 42, wherein theelectronic marshaling component is one of: an AO electronic marshalingcomponent, an AI electronic marshaling component, a DO electronicmarshaling component, or a DI electronic marshaling component.

44. The method according to any one of aspects 41 to 43, wherein thehead-end module is communicatively coupled to the controller via one ormore I/O cards.

45. The method according to any one of aspects 41 to 44, whereintransmitting the signal indicative of the registered second signal tothe head-end module comprises transmitting the signal indicative of theregistered second signal to an intervening distributed marshaling moduledisposed in the communication path to the head-end module.

46. The method according to any one of aspects 41 to 45, whereintransmitting the signal indicative of the registered second signal tothe head-end module comprises transmitting the signal indicative of theregistered second signal on a ring communication architecture.

47. The method according to any one of aspects 41 to 46, furthercomprising transmitting the signal indicative of the registered secondsignal from the head-end module to the controller, via an I/O card.

48. A process control system operating to control a process in a processplant, comprising: a plurality of process control field devices; aninput/output (I/O) card communicatively coupled to the plurality ofprocess control field devices; a controller, communicatively coupled tothe I/O card and receiving, via the I/O card, data from the plurality ofprocess control field devices, and operating to send, also via the I/Ocard, control signals to one or more of the process control fielddevices to control the operation of the process; a distributedmarshaling module comprising: a first communication port; one or moreelectronic marshaling component slots, at least one electronicmarshaling component slot having disposed therein an electronicmarshaling component; and a respective terminal block corresponding toeach of the one or more electronic marshaling component slots, theterminal block for the at least one electronic marshaling component slotbeing communicatively coupled to one of the plurality of field devices;a microprocessor, coupled to the first communication port; and ahead-end module comprising: a first communication port coupling thehead-end module to the I/O card; a second communication portcommunicatively coupled to the distributed marshaling module; a memorydevice having stored thereon a database storing information received bythe microprocessor via the second communication port; and amicroprocessor, coupled to the memory device, configured to: receive andtransmit data via the second communication port; store received data tothe memory device; retrieve data from the memory device; and transmitretrieved data to the controller via the I/O card.

49. A process control system according to aspect 48, wherein thecommunication port on the distributed marshaling module cooperates withthe second communication port on the head-end module to pass databetween the distributed marshaling module and the head-end module.

50. A process control system according to either aspect 48 or aspect 49,wherein the process control system comprises a plurality of distributedmarshaling modules.

51. A process control system according to any one of aspects 48 to 50,wherein the electronic marshaling component is configured to receive asignal from the one of the plurality of field devices and to convert thereceived signal from a first form to a second form.

52. A process control system according to any one of aspects 48 to 51,wherein the distributed marshaling module further comprises: a scanningmodule operable to scan each of the electronic marshaling componentslots and, for any slot in which there is an electronic marshalingcomponent, to register a value associated with the slot.

53. A process control system according to aspect 52, wherein themicroprocessor on the distributed marshaling module functions as thescanning module.

54. A process control system according to either aspect 52 or aspect 53,wherein the microprocessor on the distributed marshaling moduletransmits the value associated with the slot on the communication portof the distributed marshaling module.

55. A process control system according to any one of aspects 48 to 54,wherein the I/O card is disposed on the head-end module.

56. A process control system according to any one of aspects 48 to 55,wherein the electronic marshaling component is one of an AO electronicmarshaling component, an AI electronic marshaling component, a DOelectronic marshaling component, or a DI electronic marshalingcomponent.

57. A process control system according to any one of aspects 48 to 56,wherein the microprocessor on the head-end module is further configuredto: receive data from the controller via the I/O card; associate thedata received from the controller with a destination address specifyingone of a destination distributed marshaling module associated with aspecific one of the field devices, a destination electronic marshalingcomponent associated with the specific one of the field devices, or thespecific one of the field devices; and transmit the data received fromthe controller, and the associated destination address, to the specificone of the field devices by the transmitting the data on the secondcommunication port.

58. A process control system according to aspect 57, wherein thedistributed marshaling module comprises a second communication port andwherein a first one of the first and second communication ports on thedistributed marshaling module is communicatively coupled to the secondcommunication port on which the microprocessor on the head-end moduletransmitted the data, and further wherein: the microprocessor on thedistributed marshaling module receives the data transmitted from thehead-end module, determines whether the destination address isassociated with the distributed marshaling module, and: if thedestination address is associated with the distributed marshalingmodule, routes the data to the specific one of the field devices, if thedestination address is not associated with the distributed marshalingmodule, transmits the data and the associated destination address on theother of the first and second communication ports on the distributedmarshaling module.

59. A process control system according to any one of aspects 48 to 56,wherein the distributed marshaling module comprises a secondcommunication port and the second communication port is communicativelycoupled to a second distributed marshaling module.

60. A process control system operating to control a process in a processplant, comprising: a plurality of process control field devices; aninput/output (I/O) card communicatively coupled to the plurality ofprocess control field devices; a controller, communicatively coupled tothe I/O card and receiving, via the I/O card, data from the plurality ofprocess control field devices, and operating to send, also via the I/Ocard, control signals to one or more of the process control fielddevices to control the operation of the process; a plurality ofdistributed marshaling modules, each distributed marshaling modulecomprising: a pair of communication ports; a plurality of electronicmarshaling component slots; an electronic marshaling component disposedin an electronic marshaling component slot; and a respective terminalblock corresponding to each of the plurality of electronic marshalingcomponent slots, the terminal block for the electronic marshalingcomponent slot in which the electronic marshaling component is disposedbeing communicatively coupled to one of the plurality of field devices;and a microprocessor, coupled to the pair of communication ports; and ahead-end module comprising: a first communication port coupling thehead-end module to the I/O card; a second communication portcommunicatively coupled to a first one of the plurality of distributedmarshaling modules; a memory device having stored thereon a databasestoring information received by the microprocessor via the secondcommunication port; and a microprocessor, coupled to the memory device,configured to: receive and transmit data via the second communicationport; store received data to the memory device; retrieve data from thememory device; and transmit retrieved data to the controller via the I/Ocard, wherein a first of the plurality of distributed marshaling modulesis communicatively coupled to a second of the plurality of distributedmarshaling modules by a communication link between a first of the pairof communication ports on the first of the plurality of distributedmarshaling modules and a first of the pair of communication ports on thesecond of the plurality of distributed marshaling modules.

61. A distributed marshaling module for coupling field devices in aprocess plant to a controller in the process plant, comprising: a pairof communication ports; a first number of electronic marshalingcomponent slots; a second number, equal to the first number, of terminalblocks, each terminal block in communicative connection with one of theelectronic marshaling component slots and configured to becommunicatively connected to a respective one of the field devices; athird number, less than or equal to the first number, of electronicmarshaling components disposed in the electronic marshaling componentslots, each of the electronic marshaling components configured toreceive a signal from the respective one of the field devices and toconvert the received signal to a format compatible with an I/O card; anda microprocessor coupled to the pair of communication ports, themicroprocessor configured to: receive data on both of the pair ofcommunication ports; transmit data to a head-end module on a first ofthe pair of communication ports; and transmit data to anotherdistributed marshaling module on a second of the pair of communicationports.

62. A distributed marshaling module according to aspect 61, furthercomprising a scanning module operable to: scan the electronic marshalingcomponent slots; receive the converted signals from each of theelectronic marshaling components; and either communicate the receivedconverted signals to the microprocessor for transmission to a head-endmodule, or store the received converted signals in a memory device forlater retrieval and transmission to the head-end by the microprocessor.

63. A distributed marshaling module according to either aspect 61 oraspect 62, wherein the microprocessor is configured to: receive dataincluding a destination address; determine whether the destinationaddress is associated with the distributed marshaling module; and eithertransmit the received data via the second of the pair of communicationports if the destination address is not associated with the distributedmarshaling module and not associated with the head-end module, or routethe received data to a field device communicatively coupled to aterminal block on the distributed marshaling module, by routing thereceived data to the electronic marshaling component corresponding tothe field device.

64. A distributed marshaling module according to aspect 63, wherein thedestination address specifies one of: (1) a head-end; (2) a field devicecoupled to the distributed marshaling module; or (3) a field devicecoupled to another distributed marshaling module.

65. A distributed marshaling module according to aspect 63, wherein thedestination address specifies one of: (1) a head-end; (2) an electronicmarshaling component associated with the distributed marshaling module;or (3) an electronic marshaling component associated with anotherdistributed marshaling module.

66. A distributed marshaling module according to aspect 63, wherein thedestination address specifies one of: (1) a head-end; (2) thedistributed marshaling module; or (3) another distributed marshalingmodule.

67. A head-end module for coupling field devices in a process plant to acontroller in the process plant, comprising: a first communication portcommunicatively connecting the head-end module to a first distributedmarshaling module; a second communication port communicativelyconnecting the head-end module to a second distributed marshalingmodule; a third communication port communicatively connecting thehead-end module to an I/O card, the I/O card communicatively connected,in turn, to the controller; a memory device; a microprocessor, coupledto the memory device, and configured to: transmit and receive, via thefirst communication port, first data to and from field devices coupledto the first distributed marshaling module; transmit and receive, viathe second communication port, second data to and from field devicescoupled to the second distributed marshaling module; store the receivedfirst data and second data to a database disposed in the memory device;retrieve the received first data and second data from the database;transmit the retrieved first data and second data to the controller viathe I/O card; receive third and fourth data from the controller via theI/O card; transmit, via the first communication port, the third data tospecified ones of the field devices coupled to the first distributedmarshaling module; and transmit, via the second communication port, thefourth data to specified ones of the field devices coupled to the seconddistributed marshaling module.

What is claimed:
 1. A distributed marshaling module for coupling field devices in a process plant to a controller in the process plant, comprising: a pair of communication ports; a first number of electronic marshaling component slots; a second number, equal to the first number, of terminal blocks, each terminal block in communicative connection with one of the electronic marshaling component slots and configured to be communicatively connected to a respective one of the field devices; a third number, less than or equal to the first number, of electronic marshaling components disposed in the electronic marshaling component slots, each of the electronic marshaling components configured to receive a signal from the respective one of the field devices and to convert the received signal to a format compatible with an I/O card; and a microprocessor coupled to the pair of communication ports.
 2. A distributed marshaling module according to claim 1, wherein the microprocessor is configured to transmit and receive data on the pair of communication ports.
 3. A distributed marshaling module according to claim 1, wherein the microprocessor is configured to transmit on a first one of the pair of communication ports by default, and to receive on a second one of the pair of communication ports by default.
 4. A distributed marshaling module according to claim 3, wherein the microprocessor is further configured to transmit on the second one of the pair of communication ports instead of the first one of the pair of communication ports if the microprocessor has not received an expected periodic heartbeat signal on the first one of the pair of communication ports within a predetermined period of time prior to transmitting.
 5. A distributed marshaling module according to claim 1, wherein the microprocessor is configured to transmit a periodic heartbeat signal on each of the pair of communication ports.
 6. A distributed marshaling module according to claim 1, further comprising a scanning module operable to: scan the electronic marshaling component slots; receive the converted signals from each of the electronic marshaling components; and either communicate the received converted signals to the microprocessor for transmission to a head-end module, or store the received converted signals in a memory device for later retrieval and transmission to the head-end by the microprocessor.
 7. A distributed marshaling module according to claim 6, wherein the microprocessor is configured as the scanning module.
 8. A distributed marshaling module according to claim 1, wherein the microprocessor is configured to: receive data via one of the pair of communication ports, the received data including a destination address; determine whether the destination address is associated with the distributed marshaling module; and either transmit the received data via one of the pair of communication ports if the destination address is not associated with the distributed marshaling module, or route the received data to a field device communicatively coupled to a terminal block on the distributed marshaling module, by routing the received data to the electronic marshaling component corresponding to the field device.
 9. A distributed marshaling module according to claim 8, wherein the destination address specifies one of: (1) a head-end; (2) a field device coupled to the distributed marshaling module; or (3) a field device coupled to another distributed marshaling module.
 10. A distributed marshaling module according to claim 8, wherein the destination address specifies one of: (1) a head-end; (2) an electronic marshaling component associated with the distributed marshaling module; or (3) an electronic marshaling component associated with another distributed marshaling module.
 11. A distributed marshaling module according to claim 8, wherein the destination address specifies one of: (1) a head-end; (2) the distributed marshaling module; or (3) another distributed marshaling module.
 12. A method of communicating data from a field device in a process plant to a controller in the process plant, the method comprising: receiving from the field device, at a terminal block, a signal representative of the data; converting, in an electronic marshaling component communicatively connected to the terminal block, the received signal to a second signal; registering the second signal from the electronic marshaling component; and transmitting, from a microprocessor, to a head-end module remote from the microprocessor and the electronic marshaling component, via either a first communication port or a second communication port, a signal indicative of the registered second signal.
 13. The method according to claim 12, wherein the signal indicative of the registered second signal is transmitted to the head-end module via the first communication port, by default, and via the second communication port if no periodic heartbeat signal is detected on the first communication port within a predetermined period before transmitting.
 14. The method according to claim 12, wherein the electronic marshaling component is one of: an AO electronic marshaling component, an AI electronic marshaling component, a DO electronic marshaling component, or a DI electronic marshaling component.
 15. The method according to claim 12, wherein the head-end module is communicatively coupled to the controller via one or more I/O cards.
 16. The method according to claim 12, wherein transmitting the signal indicative of the registered second signal to the head-end module comprises transmitting the signal indicative of the registered second signal to an intervening distributed marshaling module disposed in the communication path to the head-end module.
 17. The method according to claim 12, wherein transmitting the signal indicative of the registered second signal to the head-end module comprises transmitting the signal indicative of the registered second signal on a ring communication architecture.
 18. The method according to claim 12, further comprising transmitting the signal indicative of the registered second signal from the head-end module to the controller, via an I/O card. 